Your 9 year old son
From Create Your Own Story
You walk into your son's room without knocking, and sure enough, find him naked in his bed, jerking off. His eyes are closed so he doesn't see you start to stroke your own cock in rhythm with him. It's then that you notice he isn't naked at all, in fact he's wearing his older sister's panties! One of his hands works his cock, the other plays with his balls. The sight of him makes you even harder than you were before.