I read a hentai on he quiet a while ago. A group of boy change the girls and boys locker rooms sign in the hopes of catching a girl in the shower. The main girl enters and I believe gets caught by the main guy. At which point the group of guys walks in and the main one hides the girl and pretends he is the only one in the shower stall, silent sex starts by "accident" while the group is unaware. When they leave the main guy and gal move onto the floor of the locker room.
That's all I remember. Help me fakku members! Your my only hope!