Ever been playing M. C. Kids and started up the wrong level? Or maybe you screwed something up beyond repair and just need to start over?

Well, then I've got some good news for you!

Just pause the game (by hitting Start, natch)

And then hit Select. Done right, you'll lose one of your lives

But you'll get kicked back to the Map Screen. So I'd say the trade's worth it... unless you're on your last life... then you might want to reconsider.