Said when you see a hot girl (or even just a picture) that makes you want to drop and unload. Can also be used as an adjective for a hot girl. Also see fap.
Faptastic is a word used to describe a picture or video that includes an attractive woman to whom you could fap to; however, said woman may not be blatantly revealing. Cleavage is fine. Very fine.
Faptastic can also refer directly to the woman that is in the picture or video.
Guy 1: "I wish Jessica Alba would take her clothes off for the camera sometime."
Guy 2: "Meh, she's got plenty of faptastic pics and vids."