Wearing a pair of whitey tighties on your head so your eyes see out the leg holes and you can feed yourself through the Y-front.
Talking alone/to yourself. I do it sometimes when alone but it makes you look like a crazy person if you do it in public
Keep a grin on your face while maintaining eye contact, freaks people the hell out.
Drinking out of an open ended cup
Wear your pants and shirt backwards.