When your having a really boring day at work and there is nothing else to do but add random words to urban dictionary and hope a customer walks throught the door and you can sell them a damn computer.
Fantastically crappy. Something or some situation so crappy that it is barely to be believed. Akin to calling something "fantastic" in a sarcastic voice.
I went to a concert last night, and the motherfucking, craptastic audience made so much goddamned noise that I couldn't hear the music.