We don't only have five senses. Napoleon wasn't actually short for an 18th-century Frenchman. Caffeine doesn't dehydrate you. Swimming after you eat won't cause cramps.
Basically, everything you think you know is wrong, as this fascinating graphic from Information is Beautiful shows. (Click through on the link for the full graphic, which has more than 50 debunked myths.)
You may even discover new myths you hadn't known about, like the widespread rumors that George Washington smoked pot.