One kind of biceps stretch can be done anywhere that has a wall. Position the arm from the hand to the inner elbow against a wall and turn the body away from it exhaling slowly. This allows the stretching to occur in the biceps as well as the pectoral muscles. Hold this pose for 30 seconds and release slowly.
Another way to stretch a biceps is to clasp the hands behind the back with palms facing each other. Straighten the arms slowly and rotate the hands so they face down and lift the arms up. This can stretch the biceps, shoulders and chest at the same time