I have a pet peeve. I feel really put off when I hear someone saying "I can't drink cold drinks during my period or I'll get a stomach ache" and other old wives' tales.
Following these old wives' tales puts restrictions on yourself, and once you follow one, you're gonna have to follow another one and before you know it, you're busy counting the number of times you turn the lock on your door, the number of steps it takes to the bathroom from the bed and the number of times you brush your teeth from left to right.
Get with the times, people! Listen to Jamiroquai, bounce around the room and get rid of the superstitious shit people have been telling you. Use your own brain and the tools we have... if you hear a superstition you're not sure about, go search for it online, go watch Mythbusters... just don't follow something blindly and expect me to follow it too when the reason you give me is "cuz my mother told me".
(Incidentally, my sister tells me that she read in her Girlfriend magazine that drinking cold drinks during your period causes cancer cuz apparently, it clots your blood (??) and could form something that causes cancer *shrug*)