Cheat Mode:
Simply hit ESC to bring up the Main Menu and type one of the words below to enable the cheat. If successful, the menu will disappear (non-US versions only) and the cheat will be activated. Type slowly and carefully to ensure correctness.

PooSheep     When Pastoral sheep stop, instead of grazing they will poo on the floor. 
FatSheep     Sheep will grow to 150% of their normal size. This does not affect collision detection, only graphics. 
MiniSheep    Sheep will shink to 1/2 their normal size. Again, this does not affect collision detection. 
CancelCheats This will deactivate cheats and return you to the normal game.           

Note: Only the "PooSheep" cheat will work in the US version of Sheep. The other cheats were added into the game AFTER the US version was complete.

Thanks to Revolution reader Little Boy Blue!