Carrying on in a gay and/or homosexual manner in public...usually involving two completely heterosexual male friends.
"Sergio, Eddie...look, I know you guys are excited about going to Magic Mountain, but you don't have to hold each others hands...please, stop fagging off."
When twomale's either homosexual or sometimes not engage in sexual intercourse or foreplay.
Fagging off can also be used to create a sense of discomfort around non gay men!
Tom "you where drunk last night Dave, you actually started fagging off with Tim"