Ballbusting Sister

My sister, who is a year and a half younger than me, is a reall ballbuster, and I mean that literally. About the time she and I came into our sexual maturity, I was jerking off a lot, like any other guy. She, on the other hand, became sex-crazed. Having no better opportunities, she turned to me for her first sexual experience and education. She just wanted to see what a penis was like. I was more than willing to show her. On an afternoon when my parents went out shopping together, leaving Britt and me home alone, she talked me into getting fully nude. Why I didn't require the same of her, I'll never know. It was certainly a missed opportunity. On later occasions, I did see her nude, and even stuck my fingers deep into her body, much to her delight. Anyway, as soon as we decided I was going to show her my 'stuff' that first time, I was rock hard. As I pulled off my pants and underwear, she was amazed by my erection. Not knowing anything about it, she thought penises were always large like that. "Doesn't that bother you?" she asked. "No more than your boobs when you run and jump around." I answered. She reached out and grabbed my dick, and started playing with it. Needless to say, at my very minimal level of experience, I didn't last but a minute before I was pulsing out cum. Her eyes were wide as saucers, watching me ejaculate. She wanted to keep handling my dick, but I was wincing with that feeling one gets right after cumming, in which the slightest touch of the penis is too much. So, she resorted to feeling my balls in my scrotum. She was not gentle. I probably shouldn't have told her that they're rubbery, like chicken gizzards, and not fragile, as she had assumed. So, she just grabbed and squeezed. I yelled in pain, and she dropped my scrotum like a hot potato. Not without laughing her head off, however. I laughed too, after recovering from the momentary pain. OK, so you'd think the little show and tell session between brother and sister would be a one-off deal. She got to see my penis, and that was that. But no, I had to put my foot in it a couple of days later, and suggest she show me her vagina. For some reason, I wasn't the slightest interested in her tits. That's doubly odd, since I am now a dedicated breasts guy. I love female breasts. Especially, big, puffy ones. But that's just me. I can understand other guys liking other things. Like my friend Paul, he likes flat girls. I think he's part-gay, like me, but that's another story. And, Will likes asses. I mean, he just goes nuts whenever he sees porn featuring a female ass. Anyway, Britt showed me her vagina, and even went so far as to show me how to give her an orgasm. Another oddity: We both totally ignored her asshole. I mean, I saw it that day, but it meant nothing to me at the time. I've since come to really like female assholes too, and I have to admit, I won't shy away from sticking my finger in a male asshole when the opportunity presents itself. But here's the thing. After making Brittney cum, she wanted to do me again. Of course I was all for that. But instead of giving me a handjob or something, she wanted to massage my balls. She started out gentle enough, but pretty soon she was squeezing the living bejeepers out of them. It was hurting like hell. And yet, I was rock hard, and loving it. And in a couple of minutes, I came buckets, and my dick hadn't even been touched. She's worked my balls like that several dozen times since then. I usually love it every time, but sometimes I just can't take the pain. That doesn't stop her. She just squeeezes away, laughing her head off. And that's not all. I've met four of her boyfriends who have each told me she does the same thing to them. According to them, she doesn't even want reciprocation sometimes. She just wants to squeeze their balls. I don't exactly know if they are her boyfriends or just guys she squeezed. I think Britt is becoming a nymphomaniac of sorts. She just loves hooking up with guys for the sole purpose of squeezing their nuts. Weird, eh?