In the Underground portions of Super Mario Bros. it's real tempting to try and get up to the ceiling, that way you can just kind of run to the right as fast as you can without worrying about trying to avoid the obstacles in front of you. But usually it's kind of hard to get up there.

Unless...

I alluded to this earlier, but if you scroll the screen so that one column of bricks is halfway scrolled off the screen and then start breaking them

You'll notice that Mario (or Luigi) can fit in the gap, and he'll kinda get stuck

Keep on jumping until you're at the top of the screen!

Making it much easier to pass these stages.