I don't know if slang is the best representation of culture. I went to 4 of the 5 boroughs in NYC (sorry, I'm never going to Queens), and most people didn't use that term. Anecdotal evidence, I suppose. Usually, people let their burns stand by themselves.
From Urban Dictionary:
Burn:
"To be thoroughly humiliated or insulted to the point where you cannot return with a comeback."
So if it's also a synonym for "just kidding," than people in NYC must be out of the loop (no offense!).
And I think we're destined to do this forever.