Martini of course, what I remember from the book. wikipedia has it: The title, taken from the well-known slogan for Wheaties breakfast cereal, crops up in a key scene late in the novel when a waitress, apparently ironically, says "Breakfast of Champions" each time she serves a customer a martini. Vonnegut, in his typical sarcastic manner, mocks the legal and copyright systems as he notes meticulously that Breakfast of Champions is a registered trademark of General Mills, Inc. for its breakfast cereal products, and that his use of the term is not "intended to disparage their fine products."