I looked at saw my sister and her friend studying on the stairs. I was above them and could look down their open blouses. Neither one was wearing a bra, and I was trying to catch some nipple.
My name's Pete and I'm 18 and in my senior year of high school. My sister, Jill and her friend, Hannah, are both 20 and in college. Both girls are average in height and weight. Jill had very pale medium size tits and small areolas. Hannah also had medium size boobs, but she was Mexican, so her boobs were darker. Her areolas were also small.
Finally, they bent over far enough and I caught a glimpse of their nipples. They were really concentrating and didn't notice me, so naturally I took out my cock and started jerking it. At one point I must have leaned too close to the railing and my belt buckle hit the spindle. This caught their attention and they both looked up.
"Peter! What are you doing?" Jill asked.
"What a perv!" Hannah said, laughing.
"How long have you been spying on us?" Jill asked.
"Uh, awhile I guess," I said, still stroking my cock and looking at their tits.
"I guess you like what you see, huh?" Jill asked, standing up and coming close to me.
"Ha, Peter's got his peter out!" Hannah joked. Then she reached out and ran her nails on my balls, tickling them.
I gasped.
"Hannah!" Jill said, clearly shocked.
"What?" she asked innocently.
"That's my brother!" Jill stated, like it was obvious.
"Yeah, but he's got a nice cock and balls. I mean look?"
Before I knew it, Hannah had grabbed hold of my cock and she and my sister were inspecting it closely, like a pair of medical students, which they were by the way.
Then, they took turns stroking it and squeezing, tickling and cupping my balls. Both Jill and Hannah had really soft hands and they felt amazing on my cock.
All while my cock was between the spindles of the stairs. And because of the age we live it, they took selfies with my hard cock in their hands. But just my cock and their hand, no faces. They lifted their shirts and rubbed my cock on each other's titties. Hannah liked to rub the tip of my cock on my sister's hard nipples. Jill, meanwhile, pushed my cock between Hannah's boobs, which Hannah pushed together as I tit fucked her friend.
"I'm close to coming," I warned them. Hannah quickly grabbed my cock and aimed it at Jill's medium boobs and stroked me until I shot off all over my sister's tits.
"Hannah!" Jill shrieked. "That's disgusting!"
"Oh, calm down. I'll lick it off, but only if you suck your brother's cock," she smirked.
Jill, always up for a challenge, grabbed my still hard cock and popped it into her mouth.