When Knuth implements tail call optimization, it's actually faster than iteration.
All of Knuth's loops terminate...with extreme prejudice.
The NSA is permanently parked outside of Knuth's house, hoping that he might help them crack public key encryption. Sometime last year, Knuth gave them a copy of "The Art of Computer Programming", but refused to tell them which page the algorithm was on.
Knuth taught a group of kids how to use their fingers as abacuses. It turns out that his method is Turing Complete.