When you open the Game, go to options and then go to Passwords. Change the letters in the boxes to enter the cheat. Enter the cheats below:

Code - Effect

SLSDRDL - The game gets really hard
DSRDMRM - Turtles don't suffer any damage from things
MRLMRMR - Everything that increases your health Turns into pizzas
DRMSRLR - Your health recovers gradually