This can only be done in Snowman's Land and Shifting Sand Land. Find one of the tiny boxes you can pick up, and bring it to the edge of a level, where there's an upward slope you can't get up. If you go on the slope, you'll slide right back down. With the box, jump up on the slope, and ground pound. If you don't destroy the box, it will stick to the ledge, and you'll be able to stand on the box. If you can somehow get two boxes to the ledge, you'll be able to go even higher. It's useless, but fun!
Submitted by: Dremo