While the above
list is quite
acceptable, it is not, perhaps,
complete. Neither will the following list, but it
aims to at least
fill in some of the gaps. So
here goes.
Getting to your seat in a crowded theater: No matter how you do it, or how skinny you are, it is still an awkward shuffling of feet interspersed with 'Excuse me's and 'Pardon me's and 'Sorry's. "Now a question of etiquette: as I pass, do I give you the ass or the crotch?"
Stalling your car: Especially in the middle of traffic and everyone behind you honking. Just start the car, drive away and hope no one you know saw.
Accidental and uncontrollable bowel movements: Pretty self explanatory, I think.
Lifting up your arm to reveal either sweat or deodorant stains: Sure it might be hot in the room, or you might use a lot of deodorant, but it just looks dirty.
Getting caught naked alone or otherwise: They look at you, mouth gaping wide. You look back. They leave. You avoid the obvious conversation for months or perhaps forever.