Best Cover of All Time?

By now, everyone has seen more Youtube cover videos than they'd like to ever remember. More often than not, they're of people haphazardly limping through their rendition of a song but once in a while you stumble across some magic. 

Tongo's vocal cover of System of a Down's Chop Suey is the magical equivalent of an intergalactic laser cat battling a leprechaun mounted on a unicorn atop a rainbow.