To have one's body enhanced via Plastic Surgery, especially breasts or butt.
Origin: Miami (Florida) slang- "M" = Miami
or after Miami Plastic Surgeon Michael S. of Bal Harbour, Florida (Known as Dr. "M" among South Beach model types.)
Jessica Simpson must have got totally M'ed, her funbags look much bigger and bodacious!
Have you seen Billy's little sister since she got M'ed? He just became my new BFF.