Bicep excersizes requiring no equipment & do-able in a 6x2ft area?

put your arms infront of you at chest level as if you were holding a ball. have your hands about 4-6 inches apart. Flex your biceps as hard as you can, and twist your hands in opposite directions. this is a form of resistance training, where you work out by forcing your muscles to overpower themselves. It works great, and requires no equiptment, and very little space.