Check out Knuth's interview at NPR. He describes how he used graph theory to figure out how to arrange the stuff in his kitchen and ended up having the waste basket in the center of the kitchen because everything wanted to be next to the waste basket. Among other stuff, he also describes how he amuses himself by trying to figure out what would be the most optimal way to brush his teeth.
None of this stuff surprised me but what actually did was that he doesn't use email and keeps wearing his bike helmet inside to avoid having to wear it again when he goes outside.
Whatever; the truth is that... Knuth is God!