Someone who fucks cadavers. Stemmed from the phrase mofo. A mofo is a motherfucker, and a cafo is a cadaver fucker. A cadaver is a dead body. The A is pronounced like in "cafe" or like in caffienated. But not quite. Because this is cafo. Not caffienated. Duh.
"God, what a cafo!"
"Eww, you're such a cafo."
"Guess what? I just heard that MEG MALM is a CAFO."