Vaudeville: True enough. In fact, I can only use that around close friends who are already familiar with the original quote. If I said something like that to anyone else, they'd think I'm being an ass.

It would be bad: You have to use it in the proper context as a gross understatement. As in every atom in your body exploding at the speed of light would be bad. True, the same line has been used as an understatement in other movies, but the Ghostbusters instance sticks out for some reason.