Nutmeg is a
football (or
soccer if you prefer) term, for when a player threads the football between an opposing player's legs. A nutmeg can either be part of a dribble or as a pass to another player or even a shot at goal. In any case, being on the receiving end of a nutmeg is deeply embarrassing for any football player. The cheekiest way to perform this is to shout 'nutmeg'
before you play the ball through your opponent's legs.
The origins of the term are unclear, one explanation is that nutmeg is cockney rhyming slang for 'leg', so playing the ball between the legs becomes a nutmeg.
http://www.businessballs.com/cockney.htm