Onomatopoeic term used, especially in hentai and Sexy Losers, a hentai parody of sorts, to describe the sound produced by masturbation ("Fapfapfap").

The term's use and reuse has resulted in something of a "fap" internet subculture. "To fap" is now a well-established verb among many. If someone explains that their sudden uncharacteristic use of "u" for "you" and "ne1" for "anyone" is due to the fact that they are currently "fapping", and restricted to the use of one hand for typing, the rules of internet etiquette state that you should not mock them as you would otherwise.

I have also, in my inter-net experiences, heard repeated use of phrases such as "May the fap be with you", when wishing someone luck, "To err is human, to fap, divine," when one is attempting to justify one's rampant masturbatory obsession, and "To fap... or not to fap" when one is torn over whether or not masturbation would be an appropriate use of one's time.

On the other hand, I may just need new friends.