What's a "happy birthday"?
In at least the Marvel vs. Capcom 3 (and UMvC3) community, commentators of a match may exclaim this consistently when a certain event occurs. Why?
Solution 1:
The terminology occurs when you land a hit on two of your opponent's characters in this game.
The term apparently according to some sources happened to a professional player during a tournament on his birthday and since then it's become a thing.
Refer to this for more information:
http://www.gamefaqs.com/boards/637240-/63078993