When a female sets her genitals on a person's forehead; commonly performed after the receiver has passed out. This event is often photographed and used for future embarrassment.
Ryan: Brosef, did you snag a peek at that girls stomach when she lifted up her arms?
Martin: No you perv.
Ryan: She had a cramp stamp, broheim!
Martin: I hate tattoos.
To gently place your vagina on you sleeping partner's forehead in an effort to leave a short-term, sloppy impression. When your unsuspecting guest identifies the smell and warm sensation on their forehead you say, "You've been stamped!"