Not a damn thing. In fact, it feels kind of ignorantly awkward, like if someone were to find it sexy to rub their earlobe to your kneecap. "Yeah, you like that?" Not sexy. The foreskin is a wonderful and functional part of the male anatomy and I understand that their are fetishists, but people who focus solely on the foreskin itself as opposed to it as part of the entire penis. Foreskin play, to me, is about the same as if someone were obsessed with only the lower-left corner of your scrotum. If someone pinched at, licked on, and generally went ga-ga over just the lower left corner of your scrotum but didn't really use it as part of the greater package, you can imagine how foreskin play for the sake of foreskin play is borderline annoying.