Find a place in the level that has two rows of blocks, one above the other. Each row has five blocks in it; the bottom row has only brick blocks, and the top one has four brick blocks and one ? block (second from the right). Break the brick block in the middle of the top row, and then punch from below the one in the middle of the bottom row. A beanstalk will sprout and go up into the sky. Get all the way through the bonus place in the sky without falling off the mushroom platform. Jump up onto the platform at the end of the bonus place and enter the pipe above you. The rest should be obvious.
