At the end of each stage in Super Mario Bros. you get 50 points for each unit of time that you have left on the clock when you finish a stage.

But, let's say that you go to your favorite X-4 stage (the big castles)

You make your way to Bowser and bide your time a little bit (this works best if you're fiery and can get him out of the way)

And then hit the axe then the timer hits 000 seconds.

The result? When you visit the mushroom retainer the clock starts counting down from 999 time units back down to zero.

Giving you 49950 points instead of whatever amount you would have had, had you just gone for it.

And this trick is arcade only, I'm afraid.