Go to the 10th level (the second snowy level). Climb upwards (past the sweeping blocks of ice), to where the huge snowman blows you off. Get blown away, and make sure you know where your hat lands (or you may lose it forever). Now, run to the base of the second tree to your left. Wait there and you will warp. Walk away from the base and walk back to warp back. Now, warp back and forth repeatedly. Each two warps will add another hat to the pile, for some strange reason. Now, go back to your hat after a total of 8 warps or so (4 one way, 4 the other). If you run into the hat briefly, you will pick up and put on your hat, but there will still be more on the ground. If you run into the pile again, the hat you were wearing will disappear and you'll try to put another on. But, you'll immediately pick up another hat. You'll end up hat-less and holding a hat. I believe this makes you still take double damage but you can now run around holding your hat and whack badguys with it. If you leave the level, you will have your hat back on.
Submitted by: kornyhatemachine