Cows Go Moo

Alright, listen up, you silly goose. You're the type who probably thinks a square has three sides, which is kinda sad, not gonna lie. This "joke" is what we call a knock-knock. Basically, it's a setup for a silly punchline. So, here we have a 'cow' who knocks. Then, instead of a name, it's the sound a cow makes, 'cows go'. The punchline is that you expect 'Cows go who?' but then you find out it is the sound 'moo'. It's the unexpected twist of the sound of the cow. I know, it’s mind-blowing for you.