Saturday I was sitting in a talk next to PragDave, and had to boot my PowerBook (for some reason it had shut down instead of going to sleep after my talk). I took the opportunity to show him one of my favorite silly OSX features. When you type the wrong password into the login panel, it doesn't give you a message or anything. Instead, the login panel just shakes rapidly from side to side, as though your Mac is vehemently shaking its head at you.

Dave was most amused. :-)