Let's say that you're playing Donkey Kong Country. You've put in the code for 50 lives, but you've burned through most of them on a particularly difficult spot.

What do you do?

Well, you could go back to the very first level of the game, where Donkey Kong bursts out of his treehouse.

Then turn right around and go back in for a free 1up!

Once you've collected it, just pause the game and hit Select to exit the stage, and you can go back in to collect it again. Do this as many times as you need for more 1ups!

Just don't go in the bottom entrance, there's nothing there but an empty Banana Horde, which will make Donkey Kong sad, and we don't want that.