Where a person or persons are subjected to much "My chemical romance" songs. The first signs of the poisoning are a urge to dress in a Emo mana, second sign, results in the urge to sing like a banshee, the third, is an urge to perform selfharm and the last is Death, due to the last stage of the poisoning. There is only one cure for this terrible diease and this is the Mega Riff.
used as a noun to describe the diease itself:
"you have MCR poisoning"