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