First go to level 1-2. Go about half-way through the level until there is a pirana plat by some coins in the air. Below the plat there are two bricks, smah the one with the P block and smash it. While the coins are bricks, run up and go to the right of the pirana plant. Jump and a 1-Up mushroom will pop up. Quickly grab the mushroom and go into the tunnel. When you come out of the tunnel, do this process over and over until time runs out and you will have a bunch of lives.