An expression coined when one cannot think of anything else to say.
Orig: the famous Monty Python sketch about
the penguin on the television set.
Graham Chapman forgot his line/lost his place, and improvised with the word 'burma'.
http://www.youtube.com/watch?v=DnObI25aN1k
chapman: perhaps it came from next door.
cleese:
penguins don't come from next door they come from the
Antarctic!
chapman: Burma!
cleese: .....why'd you say 'burma'
chapman: I panicked