A Bushism is the humorous misuse of a word or sentence, as President Bush is known to do.
He did it again recently when he admitted that terrorists at a port could alter a "manifold" in an effort to smuggle in a bomb.
Of course, manifold has multiple meanings, none of which have to do with shipping.
A manifest is documentation related to shipp.
Oh, wait, that wasn't President Bush. It was New York Senator Chuck Schumer.