Okay, First off, don't try the 1 up hanging from the fishing pole in the forest place, unless you have ALOT of time on your hands.
Okay, what you need to do first is make sure you don't have power ups, mushrooms, or anything. Make sure your just a little Mario/Luigi.
Next, go to World 2 Donut secret 1.
After starting the level, just keep swimming forward until you see a blue tunnel, this tunnel is at the top of the screen, in a little hole in the roof kinda, go in that tunnel.
When you go into the tunnel, you should be on flat ground. Hit the "?" block, and get the ballon thing, then float up in the air and hit that koopa on the head, causing him to fall. Now wait until you de-ballon or whatever, then jump on the koopa's head, grab his shell, and go out the opposite tunnel you came in.
NOTE:once you come out back into the water, you will start going forwards, so be carefull that the red shell you have doesn't hit and kill the fish in front of you. Go out of the tunnel, dodge all fish you see, making sure the red shell dosent touch one of them (because without the red shell, this glitch can't work) you should get to a spot with 2 blue boxes on the top, (and nothing in between the boxes), and nothing below also, those blue sleeping fishes will be trying to chase you, so just swim back and forth and eventually they will disappear.
Once all of the blue fishes are gone, make Luigi sit on top of one of the blue boxes. (you should still be holding the shell) and the shell should be above the gap between the 2 blue boxes. Throw the shell down into that gap, and now it should either be randomly moving between the boxes, or just sitting there.
It doesn't matter if it's just sitting there, or moving.
Now simply have Luigi swim above it, then make him fall on it. (basically just hop on top of it) the shell should start moving, and you should be getting points, just leave Luigi alone, and let him keep "hopping" on the shell, and you should start getting a bunch of 1-ups.
This gets an average of about 3 lives a second, and is a WAY better way than the lakitu idea
Please rate 10!!!!
P.s:this might take a couple try's because either, the shell hits a fish, or you die, and this is normal. Just keep trying, you will get it.
Added by: CUrLy ^.^ Jul 31st 2009, ID#12855