Girlfriend’s Sister Measures Me Up

By MissionaryStyle.

So, my girlfriend and I moved in together recently. We’ve gotten a little more serious but no mention of marriage yet. Our apartment is not too small really, as it has a guest bedroom we use as office, but each room is tiny, so the bedrooms, kitchen and living room are really close.

After a couple of months, my sister-in-law came to the apartment and stayed with us. Gotta describe them both now. My girlfriend, Sheila, is short, a little well-rounded, and light blonde.

She got a big ass and big tits, but she is not really fat. Her skin is very white, and her eyes are blue. She is 26 (my same age). Her older sister, Samantha, 30 years old, is taller, way taller, almost my size. She has black hair, almost black eyes, and her skin is a little tan.

Her tits and ass were not nearly as big as her sister’s, but she still has a good figure. Their differences are explained because they have different fathers. Samantha’s father abandoned her and her mother shortly after she was born. As a result, Sheila looks a lot more like her mother.

She was going to stay for a few weeks in the summer. Her company had her working in a faraway town for a year or so, and she would have to go back in a month.

The second day she was here, we went out for drinks to celebrate (she had come by bus into the city and was destroyed the first day, so she just crashed into the guest room, which we had readjusted as a bedroom with a bed/sofa). We drank a lot in a bar near the building, then came back to the apartment, very wasted. This time, I was the one who went into the bedroom and crashed. I slept a little, maybe half an hour, then woke up and stayed there. I could hear my girlfriend and her sister talking. They were trying to keep quiet, but they just made their voice sound like whispers in their drunkenness but were perfectly heard from the bedroom.

They talked about Samantha’s love life. Samantha had finished a relationship with a boyfriend in this town she was staying at.

“Ugh, Robert was such a boring asshole after a while. Let me tell you, Sheila. You don’t know how good we have it in the big city until you have to move into a little town. The cock selection is so small! Robert was like the only guy with a decent-sized cock there! What am I going to do now?”

“Hahaha, just fuck someone else! I am sure you will not lack candidates.”

“Oh yeah, no, obviously, look at me, bitch, please. But the problem is that all the good guys have small cocks! Robert wasn’t huge, I’ve had bigger, but he was good in bed. But that was all there was to his. I was bored of him after a month. The sex was good, which made the thing last as long as it did but, Jesus, this guy didn’t even read any book! You should have seen his living room. It was empty except for like a big TV.”

“Yeah, Carlos luckily isn’t like that. We met at the local theater even.”

“Yeah, Carlos is great. Hilarious guy. Can take a joke.”

Carlos is me, by the way, the drunk boyfriend in the bedroom listening because he is too drunk to move and the floor is moving.

“So yeah, I am done with Robert, and no one in town has a good-sized, fat cock. I’ve been sampling, believe me.”

“Oh, you dirty whore!”

They laughed.

“So, Sheila, how big is Carlos? This big? This big?”

I heard Sheila laugh. I assume Samantha was making some gestures with the hands.

“Oh, come on, Sheila. Just this big? Is that smaller than Zack? Zack wasn’t that big, and we measured it. Was it 4 inches long, 4 inches around?”

How did Samantha know the dick size of Sheila’s ex-boyfriend?

“It’s fine, really. It’s not a lot of difference. I am not even sure it is smaller than Zack.”

“But it is smaller than Jonathan! You are going backward, girl! You have to go for the bigger dicks! Look at yourself! That big ass needs a big cock!”

“Hahaha, oh, shut up, Samantha, Carlos may be listening!”

They went back to not, really whispering.

“But seriously. Jonathan wasn’t even big. Just 6 inches. Now, he also had 6 inches of girth, which is good, let me tell you, but there’s more fish out there! Bigger, fatter fish! And you are just here with a smaller guy than Jonathan? You are not advancing! Ok, how thick is Carlos.”


“Come on, Sheila! This much? This much?”

I assume Samantha was gesturing. I don’t know how thick my cock is (I know it is almost 5 inches long, but hadn’t thought of girth, really)

“Sheila! I am barely making a circle with my fingers! That’s barely a cock at all!”

“Carlos is really good in bed. Better than Jonathan!”

“I hope so.”

Now, I knew that she had had this Jonathan boyfriend with a bigger cock than mine (I didn’t know about this Zack guy), but she had told me I was better in bed. So I guess it was true if she was telling her sister the same thing.

“Sheila, I’ve fucked guys like Jonathan and Carlos. They’re OK, and I’ve fucked big cocks. Really big cocks. Even the laziest, lamest guy with a big cock was way better. Way. Better. Your vagina just, dunno, gets roughed up a lot more, and that’s fantastic. Your labia and the walls just get stretched, and it burns, and it hurts, I’ll be honest. With the bigger ones, it hurts every fucking time. But after a little while, maybe a minute, it is fantastic, no pain, just the fire in your vagina. Nothing like an average cock. You just feel slide inside yourself, and you need to be playing with your clit to come. Sometimes you come without even touching your clit. Sometimes, if their cocks are really thick, the size just tickles your clit anyway. I haven’t looked at it while fucked, but I suspect it just gets dragged along. It’s just raw, earth-shattering pleasure. You just feel owned by the big cock. It’s great. After that, fucking a regular cock is, well it’s ok, orgasms are orgasms, but it just not the same.”


“Sheila, you also have to think of the future! You moved in with this guy. What’s next? Marriage? Kids? Imagine you have male kids. You may be dooming them to a small cocked life!”

Both laughed.

“Although mother has confessed to me that your father has a much bigger cock than mine had. So maybe you have good genes. Besides, you are smaller than me, so maybe a regular cock feels big for you.”

More laughter and then silence for a while.

“Doesn’t it hurt?” I heard my girlfriend Sheila say.

“Oh yeah, I just said so. But it passes after a little while. The longest ones may hit your cervix, and that shit hurts. The best cock is long, but not too long, and as fat as possible. Listen. I have an alternative. Fisting. Have you tried fisting?”

“What’s that?”

“When they insert their entire fist in your vagina. It really hurts. No cock has a head bigger than a man’s fist, but it is kind of close to being fucked by a big cock. It really hurts, but a decent alternative to a big cock can give you some good orgasms.”

“Yeah, I am not doing that. Have you seen Carlos’ hands? They are massive.”

“Yeah, I was thinking that.”

Silence. They discussed getting more drinks, went to grab a beer from the fridge.

I Dunno what had gotten into Samantha trying to convince my girlfriend that my cock was inadequate. Maybe it was the lack of sex since she said she had no sex in a while.

Sheila broke the silence:

“You know what we should do? We should measure Carlos. I have a sewing measuring tape in the closet.”

“Ah, I knew I could talk sense into your little brain. Remember when we did that to Jonathan? The look on his face when his sister-in-law just grabbed his cock and measured him?” Samantha answered.

“And then you told him he was small. I had to give him so many blowjobs, you asshole! But since he was trying to compensate for his size, we had the best sex for a good while. You won me such a good fuck with that, Samantha.”

“Yeah, so you told me. It always works like that. Remember when we measured Wilbur? He fucked me all night after that.”

“Oh my god, Wilbur was so big. I’ve never had a bigger dick in my hand, before or after.”

“Wilbur wasn’t the longest I had, but his cock was fat, yeah. I’ve had better, but not much better. Although Wilbur fucking me that week, we measured him? Maybe some the best sex I’ve ever had, yeah.”

What was this measuring thing? Were they just gonna ask me to wipe out my cock and put a tape next to it?

“We should do it now. I could use some fucking, Samantha.”

“Is he going to be able to fuck you? He looked tired as fuck.”

“Oh no, Carlos has stamina. That’s good about him. He has fucked me drunker than this.”

“Oh, ok, let’s do this.”

I heard them move around and come to the bedroom. I had no time to react. I just shut down my eyes and pretended to be asleep. Unfortunately, the conversation had actually woke me up, and I had semi-erection.

Once they were in the bedroom, they started giggling, and I heard clothes rustling. Then I felt Sheila’s small hand move my shoulder.

“Carlos. Carlos. Wake up!”

I opened my eyes, pretending to wake up, and looked up. The bedroom was dark, but some light came from the living room that illuminated the sisters from behind. They were both naked. I couldn’t make up all the detail in the darkness, but they were stark naked.

Sheila kept her pubic hair trimmed, but Samantha just seemed to shave it all. She also seemed to have some tattoos around her vagina that I could not distinguish. Her tits were small and beautiful, and her nipples pointed out inattention. Both girls had big nipples, and they were all erect. They were excited to do this.

My eyes opened big.

“Hey, what’s going on?”

Sheila spoke. “Carlos, we want to measure your cock. You just saw us, so it is fair if we see you too.”

Samantha added, “Hey, bro. Bro in law. Sheila says she isn’t sure if you are bigger or smaller than her previous boyfriend, and we just need to know.”

Samantha lifted her left hand, and I could see the measuring tape hanging from her.

“I’m 15 cm, 5.9 inches if you want imperial.”

Samantha denied it with her head. “Yeah, men always lie about that. Even the guys with the biggest cocks I’ve sampled lie when asked about their size. They all add half an inch or even an inch. Besides, I want to know your girth.

“Zack, my previous boyfriend, was 13 cm, just 5 inches. And 4.8 inches around, which I think was what? 11 cm?”

“Twelve cm of girth. Not a lot. You have a lot of chances of winning this out, Carlos!”

“Do you two measure the penises of all your boyfriends? Is this a weird sister thing I never knew about?”

Samantha answered:

“We’ve measured both of Sheila’s previous boyfriends. Jonathan and Zack. From what Sheila tells me, you are smaller than Jonathan but maybe bigger than Zack. Maybe smaller.”

“We haven’t measured all of Samantha’s boyfriends, given she is a whore,” Samantha hit Sheila’s arm at this remark, “and she’s had a lot of boyfriends that I never met. I measured Wilbur and another guy called Jonathan. Coincidence, not the same guy.”

Samantha added, “Both bigger than her, Jonathan, although Wilbur really impressed your girlfriend here.”

“I had never seen a cock as big as Wilbur’s.”

“Or touched one as big.”

Sheila repeated sheepishly but smiling, “Or touched.

“Ok, Carlos, here’s the deal. If you get naked right now, the girl who is not your girlfriend, in this case, me, gets to measure your dick. Otherwise, your own girlfriend measures your cock later, when you two are alone, and Sheila tells me the numbers later.”

“Ok, wait. How this did start,” I asked.

“Why do you want to know?”

“I want to know what I am getting into here. Is this a full family thing? Will my mother-in-law measure me when I go meet her?”

Sheila and Samantha laughed.

“No, no. She is not into this. When Sheila was 18, and I was 22, I just walked into Sheila and Jonathan fucking one time at home, and Jonathan was all cheeky and didn’t even cover himself. One thing leads to the other, and I ended up measuring him. Sheila didn’t stop me, so I returned the favor with Wilbur a month later.”

Sheila said, “Ok, measuring time. Will you get naked?

Well, I really wanted to have my beautiful, naked sister-in-law manipulating my cock to measure it, so I just started taking my clothes away. I threw my shirt away, then grabbed my pants and underpants and dragged them out, then my socks. Finally, I stood up with half an erection.

Sheila said, “Stand up, get in front of me. She measures it, but I have to make it hard.”

“You did kiss my Jonathan’s dick head once, so that’s cheating.”

“You can NOT kiss Carlo’s dick.”

I stood, disappointed I was not getting a dick kiss from Samantha. Sheila got behind me. I could feel her big tits and pointy nipples rubbing my back. Sheila grabbed my cock from behind. It did not take a second for me to be having a full erection. Almost all my drunkenness had gone away too. Samantha sat on the bed, looking at me. She inclined herself to look at my cock, so her head was very close to it.

Samantha spoke, “Hey Carlos, are you, Latino? I have darker skin than you.”

I could feel the air from her mouth on my cock.

“My grandfather on my mother’s side was a Latino, and I was named after him, but no. As a result, I barely speak a few words of Spanish.”

“What’s Spanish for Shorty? Corto? Gonna name you Corto from now on.”

“You haven’t even measured me! You can’t call me Corto!”

“Oh, but I can tell without the tape you are a Corto. So if you let me call you Corto, I will kiss your dick.”

Sheila yelled from behind, “No kisses!

“I will lick your dick head. Can I lick his dick head, Sheila? Just with the tip of my tongue.”

“That’s worse than licking!”

Samantha insisted, “Sheila, come on.

“Ok, ok. Just the tip of the tongue.”

Samantha giggled. She stuck her tongue out, then said, “Can I call you Corto from now on? It will be our in-joke.

She stuck her tongue out and moved it, just in front of my dick. I couldn’t resist this cutie offering to lick my dick, even if a little.

“Ok, you can call me Corto if you like.

Samantha liked the tip of my cock, slowly. It was delicious to have my sister-in-law licking my cock, however fleeting the moment was. Then she tried to push her tongue down my urethra. I moaned a little. Sheila said, “Hey! No, enjoying this!”.

“Ok, Corto is now at full erection, I think.”

Samantha started measuring me. She grabbed the tape and put it around my cock, around the base. I normally cut my pubic hair, and Samantha commented on that.

“Good thinking here, Corto. Cutting your hair down makes your penis look longer. But it will not fool the tape.”

Then she grabbed the tape with one hand, grabbed my cock with the other. She made a ring with her fingers, and dragged it to the base of my cock, and then put the tape starting on the underside of my cock and dragged it to the point of it. The tape curved a little along with my cock.

Sheila added, “So yeah, this is how we define length. Jonathan had the luck of us both discussing the procedure, which leads to a lot of manipulating his cock. Basically, the cock is a cylinder, we measure from the underside to the tip, but the underside starts where the upper side meets the rest of the body.

“Yeah, it’s all very mathematical. Ok, I have good news and bad news.”

Sheila said: “Oh no, doctor, the good news first.

“He is longer and thicker than Zack. 12 cm, 4 and three-quarter inches long, 10 cm or 3.9 inches of girth.

Sheila yelled, “Wooo! Bigger than my previous boyfriend!

“He lied about his length, though. I told you.

“Is that the bad news, doctor?”

“Oh no, the bad news is worse.”

Samantha stood up. She was looking at me in the eyes. Then, she closed up, and at the same time, grabbed my full cock in her left hand.

“But he is still smaller than Jonathan, Sheila’s first boyfriend. And Corto here has a small cock, even if Zack was smaller. I’ve had cocks that I could not envelop with one hand. I rarely bother with cocks that need my one hand. My last boyfriend needed both hands.”

She looked at me, lifted her brows, and nodded.

“Yeah, you deserve to be called Corto.”

With that, she released my cock, turned around, and went out.

“Good luck with Corto, sister.”

Sheila and I were left alone. Sheila went to her knees and started sucking my cock, slowly, licking it all.”

“I am sorry my sister bullied you. She is obsessed with cock size.”

“No, it’s fine, really. That was really hot.”

She licked some more. Then tried to push her tongue inside my urethra.

“She licked you and did this. You are a lucky bastard.”

“Did you really touch your sister’s boyfriends’ cock?”

She looked at me. In the darkness, I still could see her licking my cock slowly.

“Oh yeah. At least Wilbur and her Jonathan. They had big cocks. Very, very big cocks. I measured them with my tape.”

She kept licking.

“Did you kiss their cocks? Or lick them?”

“I kissed Jonathan’s cock head. Just a little kiss like this.”

She kissed my cock head. Then she put my cock head in her mouth.

“Did you kiss or suck it? You are not clear.”

She just kept sucking and looking with her big puppy eyes at me.

“Did you have a boyfriend when you did that?”

She didn’t answer. She instead stood up, threw me to the bed, climbed on top of me, and put my cock inside her. We started fucking. She came down to kiss me. I could feel the taste of cock in her mouth.

Sheila started talking again as we picked up the pace.

“It was while I was with Zack. I kissed her boyfriend’s cock, and put its head in my mouth for a second. Then I went back to Zack, and we fucked like crazy.”

“Why did you cheat on your boyfriend?”

“It wasn’t cheating! Just…a little try of what I was missing. I wanted to see what it was to have a big cock in my mouth. Wasn’t any different, really.”

We started fucking and moaning more. Samantha surely heard from the other room. Eventually, Sheila came, and then I came inside her. She collapsed on top of me.

“Was it cheating when you let my sister lick your cock? It’s the same thing.”

We fell asleep.


The next day Samantha joked, “Hey, assholes, at least close the door when you fuck. At least it seems Corto here knows how to fuck, judging from the moans.”

Sheila laughed. “Told you, Carlos is plenty for me.

“No, no, no. Corto is his name now.”

The days passed by. Next Sunday we went dancing. We drank a little, danced some more. Samantha met some guy, and she asked Sheila if she could bring him home. Sheila said, “Yeah, sure.”

I wasn’t asked.

We took a cab home. I was sitting in the front seat. I missed what the guy’s name was. We arrived home, and Sheila and I went to our bedroom and started fucking. In the next room, we heard the guy and Samantha do the same.

Sheila moaned a little, but her sister. “Oh god,” she yelled. I am sure the whole building must have heard her yell, “OH GOD, IT’S SO BIG, SO FAT. YOUR COCK IS SO FAT, YESSSS, AAAH, AHAAAH,” for like an hour.

I came inside Sheila and fell asleep. I was woken up by the movement of Sheila standing up from the bed and walking to the next room. I heard nothing more than giggles and laughs. After a few minutes, Sheila came back. She tried to wake me up (I pretended to be asleep), and she just grabbed my cock and started masturbating me.

“Hey, wanna give it another go?”

We fucked like crazies. Something possessed Sheila, and she fucked me like there was no tomorrow. She screamed a lot, and after I came, she went down and cleaned me. Then kissed me again.

The next day, Samantha’s fuck buddy was still there at breakfast. Samantha introduced us. “Hey Corto, this is Fatso.”

I put out my hand, and this Fatso guy grabbed it.

“I’m Carlos.”

“Francis, nice to meet you.”

“No, no, no, this is Corto, and this is Fatso.”

Sheila came into the living room. “Hey, Fatso! How was last night?”

“It was great! You know it!”

Fatso took breakfast and left. We didn’t see him again, but I have my suspicions about why Sheila and Samantha called him Fatso. Samantha didn’t bring any other guys the month she was with us. So Sheila and I fucked like rabbits while Samantha was there.

Hope Samantha comes back soon, as she did a lot of good to our sex life.

The End.


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