In Vanilla Dome 2, make sure you're Fiery Mario (keep a Cape Feather in reserve for more fun) by the time you bring the first P-Switch over to your left, where you'll run through a thin wall of Coins and into a bunch of brown blocks. Stomp the P-Switch, and collect some Coins from the bottom row (run and duck). Keep ducking until the P-Switch's power stops and the Coins change back to brown blocks. Then, while still ducking, spin jump until you drop down into the wall. Inside this wall is particularly special because any object inside that isn't touching Mario will float from side to side. Mario's fireballs won't bounce; instead, they shoot straight to the other side! With careful planning you can take Yoshi with you, and even the P-Switch. Leave them above you inside the wall and watch them float back and forth.