(Note: This Idea is Eeyore's idea...I liked it a lot, so that's why it's here. o3o)
My Sisters Slave
Raiga had a big cock, especially for a 16 year old. But he was shy and none of the girls knew how big his cock was. But that was all about to change. Despite his shyness, he has taken pictures of his cock and posted them online, even exchanging pictures with some girl from Canada. His older sister catches him home alone one day, jerking off to pictures off the girl, and is blown away by the size of his dick. She also sees the pictures he's taken, still on his screen, and threatens to tell their parents...unless he does some things to her...
As shamed as Raiga was at being caught, he knows he doesn't have a choice. Things only get worse for him when she invites one of her best friends over (and a girl he has had a crush on) to marvel at how big his dick is...and his sister takes even more incriminating pictures of him. Raiga effectively becomes her sex slave, forced to her and her friends on command.
Looking for someone to play the Sister, of course, and perhaps her friend as well, if whoever wants to play the sister doesn't like doubling up.