When annoyed, agitated or just messin wit someone who is on thier way to annoying you, it siply means "eff-off"
John: Hey Cathy What you wanna do tonight?
Cathy: Go away I don'e LIKE you.
John: You know what forget you.
Cathy: Fine then, Suck my left butt- cheek!
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