Another myth I've always thought was stoopid is the swimming after you eat. Don't even mention the word swim while you're eating around my grandmother. She'll start telling you about disfigurement, maiming, and death while sizing you up for a coffin. And nothing will change her mind. O.K. not really survival related, but I guess if you have to swim across a river after eating your fill of snare caught wood rats and black berries you won't die from cramps.