Cow's Moon Job

Alright listen up, buttercup! This joke is funny because it's a pun. You see, the cow is "out of shape," meaning she's probably overweight. Then, the punchline references the nursery rhyme "Hey Diddle Diddle," where a cow jumps over the moon. So, the joke combines the cow's physical condition with a well-known rhyme. It's funny 'cause you're dumb.