Go outside the entrance to "Hungry Tonight?" Collect the Power Parp Tin from Snott and use it to collect the nearby extra life. Enter "Hungry Tonight?" and immediately exit. Talk to Snott again to get another Power Parp Tin, then collect the extra life again. Repeat this to get as many extra lives as needed.
Collect 1000 marbles and successfully complete the game with a Smart Superhero rank to unlock Earthworm Kim. The difficulty of the game will increase when played as Earthworm Kim.
Go to the Fear part of the Brain and enter the door on the right of the Sacred Cow Of Contemplation. In this room is the way to the levels Poultryguyst and Poulrtyguyst 2. You should see a door blocked by a metal gate. If you have all 1000 marbles and have beaten Earthworm Kim, the gate will open. Walk through it and the game will automatically reset. When you start the game again, Earthworm Jim usually hops around playing the accordion -- this time Kim will be the playing it and will soon be smashed by a cow. Press any button to get to the file select screen. You should now have a fourth file as Earthworm Kim.
Defeating Fatty Roswell:
Collect two of the three missiles and wait at the third. He will teleport there and be an easy target.
Ignore the marbles, collect bullets at all times, and shoot him. Keep his marble level at 0 or close to it at all times. This will allow you to get your marble level up to approximately 85 within a few minutes.
The Good, the Bad, and the Elderly: Easy Golden Udder
In the fantasy part of the brain, there is a building shaped like the back of a cow. Inside, you must ride an annoying ice cube around a room. If you fall off, you must start over. However, if you jump onto the ice cube and immediately jump back onto the fridge, then you can just watch the ice cube slide around. Simply jump back onto the ice cube once it returns to the fridge but before it stops moving. You will receive a golden udder without doing any work.