To jerk off. Comes from the sound that is produced while a man is masturbating.
She didn't put out again, it's our third date. I think I'll just fap off.
by bitofafry November 04, 2013
two begin to fap. one finishes. one continues.
there are two people who disagree about who can out fap the other and so they have a fap off
by The American American November 04, 2013