Nintendo’s got you covered. Remember the Super Mario Bros 1-UP trick? The one where you keep jumping on the green Koopa that walks down the stairs at the end of level 3-1. Nostalgia just oozes from the New Super Mario Bros on DS, because the trick’s back as you probably guessed by now.
You can do it in worlds 2-4 & 4-2, so jump away on that green shell, just keep your eye on the timer. If you want to get 99 lives without jumping, go to level 7-5 and throw a Koopa shell in between the 2 Bullet Bill cannons, cheap, I know 🙂 See how it’s done in video by clicking on “more…” below.