Didn't see any of these, but heard about them from my friends at the UW:
- McGruff the Crime Dog - this was one of my better friends, who tonight is going trick or treating for shots.
- Your conscience - another one of my friends and his roomie stuffed themselves into the shoulders ofa shirt, put a fake head on it, one was a devil, one was an angel
- The above guys' roomie went as a member of a certain sorority at the UW that is noted for being snotty, and ran around saying "You're too poor to be my boyfriend" all night
- A Mexican Mariachi Band, complete with instruments that they played
- This was a few years ago, but one of my friends went as a mammogram machine - he put a big box around his head and told women to stick their chest inside for a free inspection.