Toying with, stimulating, manipulating, using the nipples to achieve sexual satisfaction. Usually combined with sex of some sort. A peripheral pleasure stimulus.
When your talking too a friend and say Nippleatick. in which you grab one of your man boobs and smack someone on the head. preferably taking your boob out!
When you seesomeone that turns you on causing your nipples to get hard.
Damn... look at that chick over there... she be lookin' nipplelicious! (When saying this you should rub your own nipple in a circular fashion while biting your lower lip.)