Some commonly known "facts" are in fact totally incorrect. Most of us know by now that colds and pnuemonia are caused by viruses and bacteria, not because you went outside without a coat on or with wet hair - despite what your mother says.
But did you know it's okay to swim soon after eating? And that it's probably safer to wake up your sleep-walking roommate than leave them to wander the halls?
Take a look at Matthew Santoro's "7 Myths You (Probably) Believe About Your Body."