Someone who's so ugly that each time you think of her, you'd puke, so you can't have sex with her, and if you have sex with her, you'd die

a person who fucks himself

The process or act of something becoming fuckered up...

The use of everyone's favourite four-letter word inserted within another word or abbreviation.

A general pattern by one or more persons within a group of people, which ought to be platonic, professional, or otherwise non-sexual, has sex with other people within the same group.