Type in "ERMINTRUDE" and you'll be told "Sacred Cow Can't Be Harmed".
 This is all very well and good, since it means you've now got
 infinite energy, but unfortunately you can't hurt the final
 end-of-the-last-level boss with this cheat on! That is, you can't
 complete the game... Alternatively enter "PINKYANDPERKY" for the
 ability to fly by holding down "F". You can complete the game with
 this cheat on.