Nobody will put their hand up. Proof by TeX - Apologize for not being a TeX wizard, but claim that a random series of squiggles, and diverse other marks on the handout constitute a proof. Proof by Intuition - Promise a proof to be given next year, and next year say that the thing is intuitively obvious and something you've known for years. The book either has 8 chapters, or does not exist. Proof by Honesty - This really is true.
Every planet is an orange.
A round ball is a stellar object. A ball is an orange citrus fruit from which one can make orange juice. Clearly every planet is a round ball, hence surely a ball and therefore an orange. He wrote down a theorem and chalked underneath it. Right, I won't bother.