My girlfriend likes to watch me masturbate in the bathroom...
My girlfriend saw me masturbating once after I got out of the shower, in front of the mirror.. She said it was the hottest thing she ever saw. But she doesn't like me to know she's watching, and especially if she's jilling herself.. So now I always leave the bathroom door open a little for her, and whether she's watching or not, it's totally hot for me to know that she MIGHT be,-totally hot!
She would never tell me whether she was peeking or not. When I come out, she's always got her panties on and is busy doing something. And so we began a game of my trying to guess.
If I guess right, and she was, she usually is pretty sexed and wants more. My 'reward' is to help her jill her. If I guess right and she wasn't, her 'penalty' is to masturbate for me. She's very shy about jilling herself, and when she's 'forced' to do it in front of me, it's very erotic for her. (she can take a rain check if she's really not in the mood).
The only problem is that we seem to be late going out a lot!