2 'trick' plays one coach brought to my attention during the pre-game chat recently:
-one of the substitutes enters the field and then immediately the ball is snapped... he was surprised that this is illegal
-another 'trick play' he mentioned was on a punt play. He's the receiving team. He planned not to return the ball, and if the kicking team relaxed and the ball came to a stop, pick up the ball and advance it. Even when I told him it's a dead ball by that time, he went crazy when we blew the whistle when he actually tried to run it...