Mission:Mango? I haven't heard that name for it, though it's likely to come from the San Antonio crew. I coconut think of anyone else crazy enough to come up with something like that.
In Austin, we just call it The Game, and it's a more general form: if you say something self-defeating, unless it's anatomically or physically impossible, you get prizes. Keeps people from considering things to be mango instead of impossible but still keeping the negativity.