Things You'll Need
Instructions
Start the game and play through levels 1-1 and 1-2.
Play through almost the entirely of level 1-3, but do not finish the level.
Stop at the very last elevated white block that you see before you enter the black part of the screen that ends the level. This white block is in the middle of two green blocks, one blue block and one pink block.
Crouch down on the white block for five seconds until you fall behind the white block and the bushes.
Run towards the end of the stage behind the black section that ends the level. You will enter a secret room automatically.
Run towards the chest that is in the secret room to open it up. The warp whistle will in in there.