This stage is a little tricky, but it's much shorter than the others when you finally get to the top. Walk to the left and kill the ball. Enter the door after that. Head up the elevator beside you, walk to the right and then wait. The green molecule floating around will eventually go after you. Let it hit you and you'll fall to the platform below. Now kill the ball and continue to the right and the platform above the elevator will disappear, allowing you to use the elevator properly. Go all the way to the top and enter the door. You'll fall onto a platform with another elevator close by. Use it to get to the top.
Avoid the floating hamburgers at the top and head up the elevator at the far left. Walk off the left side of the elevator quickly to avoid the floating hamburger nearby. If you have to, walk to the right to avoid it and then head back to left. Climb the ascending platforms to the top, destroy the flashing bricks, and go up with the elevator. If the floating hamburger gets close, just wait until it passes before you head up the elevator. Near the top, another floating hamburger will be moving around. There's no wait to avoid this one so if you get hit by it just continue on. Enter the door at the top and then enter the next door as well. When you reappear, enter the door to finish the stage.