PMX
A maniac. One who cannot control themselves in a public situation. One who wears a pink shirt out in public and strikes out in a blind rage when someone comments on it.
He has had too much to drink. He bumped into that guy purposely to start a fight. He is a PMX.
PMX
Like PMS, but a much fiercer, nastier, extreme version.
Dude, your girlfriend looks like a bloated Mike Tyson. Must be the PMX.