Like the Cow Level in Diablo. I believe it started as an April Fools for the first Diablo but by the second they had decided to make the Hell Bovine real and a cool part of the game. I just love when the cows die, they cry out, "Moo!"
Scratchit: But he's a cripple!
Blackadder: He's not a cripple, Mrs Scratchit. Occasionally saying "Phew! My leg hurts!" when he remembers to wouldn't fool Baldrick!