When a male and a female has sex, and the male's penis is cut off by the female and the male summons a fire dragon to kill the female.
Sometimes, it can also mean:
When each end of a bottle is put into a vagina/ass of a female/male and the bottle breaks. If it is 'ass' and 'male' it is commonly known as Jewish Jesus Sausage.
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