an acronym (pronounced as a single syllable) for "Gently Flicking the End of My Penis". It can generally be exchanged in place of "joking" or "kidding" to impart a sense of incredulity.
Kevin: Dude, lemme buy you a beer?
Chris: Serious? You're not GFEMP, are you?
Kevin: Yeah, you got me...
Chris: Serious? You're not GFEMP, are you?
Kevin: Yeah, you got me...
by Cosmo July 27, 2006