1. This is about the 2 of Clubs. 2 of clubs, like in cards you know. It means "Show your boobs" or like, "Lift up your shirt and show off your juggs." It is considered the highest honor to be presented with the 2 of Clubs--not to be taken lightly or shown to just any girl with boobs. Reserved specifically for those with great ones.
2. The folkloric character Dr.Bones is said to keep a 2 of Clubs in his top hat.
Guy: (Shows girl a 2 of Clubs)
Girl: (Takes off shirt and bra)
Guy: "Damn. Those are the finest titties I have ever seen."