Pretend to be driving your sleigh, say: "Whoa!" (pulling up on the reins), get out of the sleigh, pretend to climb into the chimney, begin to slide down and struggle, say: "Wheeze, grunt, rattle, clank, oh, no," move hands as if falling trying to grasp the sides of the chimney, then yell:"Craaaasssshhhh and then put your finger to your mouth and say, "Shhhhhhh!"