This was where you would get a packet of round maize balls (usually 6p and sometimes fortified with vitamins on the premise that anyone so poor as to eat them probably didn't have a healthy diet) and then insert them one-by-one under your foreskin, then pull your flap over them until they disappeared. You would do this for as many as you could and put them back in the packet. Then you would offer them around, safe in the knowledge that if anyone called your bluff, you could quite safely put your own cock cheese in your mouth.