At the end of World 2-3 in New Super Mario Bros. Wii, you find this formation.

Look familiar?

It's strikingly similar to a formation we saw in a prior tip. Check it out

So you might be thinking you can apply the same technique: wait until the Koopa gets about halfway down the 'stair' and jump on it.

You keep bouncing, racking up points, until

1UP!

You can keep doing this for as long as there's time left on the clock, with the added bonuses of: 1. there's no bug that goes off if you get more than a certain amount of lives, 99's the limit and 2. if you need to, you can come back to this stage and do the trick again for yet more lives.

And, to help illustrate the timing, I've prepared the video below.