Here's a fun trick. If you're in a crowded public area like an airport terminal, and you see someone walking toward you while talking on a cell phone, stop and stand still. When he (or she) walks into you, he will ask you why you don't watch where you're going. Then you point out politely that you were standing still at the moment of impact. Then he takes a punch at you for being a wisess...

Well, maybe it isn't that much fun...

Peter.