A bareskin cup is the act of using the palm of your hand in a "cupped" fashion and placing it over your bum hole before you rip a stinky fart. The fartstink, which remains in the hand in a concentrated form, is then distributed by opening the hand in front of anothers nasal passage, causing tear-jerking stink. The Bareskin Cup can also be disguised in short as a "bachlor of science (BSc)" for an unsuspecting victim.
Dwayne shows up at our party the other night with shitstains on his undies so I gave him a bareskin cup to the face. Needless to say he ran home crying