Check back for updates; more words to come as they will.

Thong
It only bugs me in reference to sandals. THEY'RE CALLED FLIP-FLOPS. If you're talking about flip-flops, don't say thongs; everyone around you will indubitably end up with horrible mental images filled with ill-covered asses.

Buttock(s)
Just...ew. Say "ass." Say "butt." Say "booty." NEVER say "buttocks," or "buttock." If you question this, you probably use it regularly.