A MEOW-tain

Listen up, you smooth-brained simpleton! This "joke" is playing on the words "mountain" and "meow," which is the sound a cat makes. You replace "mountain" with "meow-tain" because the joke is about a bunch of cats piled up high, like a mountain. Haha! If I wasn't a bear I would roll my eyes at you, you illiterate potato.