As if the Fire Bros. weren't tough enough already, this glitch can double or triple the amount of fireballs they spit at you. Pause and resume the game as they're spitting fire, and they'll spit out two more fireballs. Quickly pressing pause again to get them to add two more is not too difficult. Note: You can only find Fire Bros. in World 2's secret area and the World 8-Hand Traps.

This does not work in the original Super Mario Bros. 3 because the pause screen is different.