I sat the Human Performance exam after a few drinks -- how's that for ironic! Still passed with over 90% though, and it only took me 7-8 mins to do it. The easiest exam, for sure, so save it for some time when you can't do anything else (eg when the weather is crap, you're exhausted, you're suffering brain overload from attempting to learn how to use the whizzwheel, and you're drunk!!).