Definitions by Huahahahaha

C.T.F.I.

Cum The Fuck In -
It is usually used by the female role in sexual intercourse, but sometimes may be treated as the polar opposite of G.T.F.O.

Man: You'd better let go, baby! I'm about to cum.
Woman: C.T.F.I., Baby!
Man: What? I don't u....uaaAAAGH!