When one needs to do a tactical yack after consuming to much alcohol and so, instead of a normal vomiting position, the person positions themselves on all fours and imitates a cat vomiting (whilst vomiting)
'Hey, I'm feeling like I need a tac yack'
'No worries, just perform a sick cat'
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