Similar to "ROFL" (rolling on floor laughing), "LMAO" (laughing my ass off), and "LOL" (laughing out loud), this expression means "My ass fell off while laughing." This acronym was made for the grammatically correct group that wishes to express their experience of a hilarious situation whilst also remaining somewhat intelligent.
"Dude! This guy thinks he can pwn me MAFOWL."
by Entheory December 15, 2009