Instantly Excited!

I have been dating my girlfriend for over two and a half years now. Her sister is five years older than us. Every now and then, I go over to my girlfriend's house and have to wait for her to get home from work. During this time, I am at their house alone. When I'm at their house alone, I go into her sister's room and rummage through her underwear drawer. When I find a thong or some panties I like, I borrow them. I then go lie in the sister's bed and masturbate. I always wipe them clean. One time when I did this, I wiped them, returned them, and then later I caught a glimpse of the sister wearing them. I was instantly excited!

— Troy, 19