It's actually a contraction of "my bad choice" and it can apply to words or deeds. It started about five years ago, and has been increasing yearly to the extent it's now universal, even making inroads to Australia.
It's part of the living language of course, and belongs in the same category as:
"24-7",
"OH. MY. GOD.",
"are you serious?"
"loo-oo...ZERRRR"