When you deficate into your lover, partner or random drunk-hookup's mouth, then make them puff their cheeks out as you smash them together, exploding shit and saliva everywhere.
Man, I can't get the shit-zitstain out of my cardigan sweater!
Boys who enjoy yaoi (a genre in Japan that contains sexual and/or romantic relations between two men); literally translates to "rotten boy"; corresponding female : fujoshi