When a man bleeds out of his asshole, much like when a woman has her period. It is caused by a lot of stress or depression. No one is sure why this happens, hence the name enigma. It is mentioned in the Lil Wayne song 6 Foot 7 Foot when he says "what's the world without enigma?"
Guy 1: Did you hear about Mike?
Guy 2: No, what happened?
Guy 1: Stephanie broke up with him and he enigmad all over the place