1. Seeing as fap is the sound made when masterbating, and offbeat fap is a "fap" sound that is offbeat, suggesting someone else is masterbating as well.
2. when you hear the sound of someone else jacking off in the room 3. Something utterly horrible.
1. fap....fap....fap..FAPFAP....... WHAT THE FUCK WAS THAT?!
2. Dude, I was masterbating last night when I heard an offbeat fap, I turned around and my brother was right behind me fapping away.
3. John: Dude check out this picture of this hermaphrodite.
To touch oneself in a manner that produces a "fapping" sound often resulting in wasted kleenex and dick cheese. Due to lacking alternatives, it's popularity has constantly risen since women were given rights.
John: Hey Joe, seeing as you're apathetic loser who can't seem to get a girl, would it be a stretch to say that you fapoffsturbate whilst self-inducing asphyxiation to help yourself fall asleep at night?
Joe: ... huh...?
John: Oh, I'm simply implying that you have a lot of time on your hands.