In the original Super Mario Bros. game, once Mario gets Fire Power, all kinds of weird things become possible.

For instance, find a pipe or the beginning of a stage that isn't a water stage or underground, and before the stage starts or you come out of the pipe, hold a direction (either one will work) + Fire + Jump. Done right, you'll jump up and then hit the ground sliding on one foot.

This will wear off after a few seconds, or if you shoot another fireball. And I haven't really been able to find much of a use for it, other than making Mario look foolish for a few seconds. But maybe you can.