While in the Hazy Maze Cave, get into the Hazy Maze itself. Kill eight of the moles in a row, you will get a 1-up. Make your way to the lone mole on the other side of the maze, kill him eight times, get a 1-up. Now go back to the first pair of moles, kill eight in a row and a THIRD 1-up mushroom will appear! Continue going between the moles for the desired amount of lives.