CM Punk is a retired professional wrestler who was most known for planting pipebombs inside the WWE Studios. In 2013 he was promptly removed from the building for snorting the ashes of The Undertaker's manager, Paul Bearer. In 2015, CM Punk retired from WWE, married fellow WWE diva AJ Lee and has since signed with UFC, but has yet to participate in a fight. He's probably just a pussy.
Fans have speculated the origin of his name "CM Punk". Some believe it is Chicago Made Punk because that's where he was born, others Chick Magnet Punk based on an old gimmick. Well they're wrong. It stands for Cranberry Muffin Punk.