Yo Mama and the Rams

Listen up, buttercup! Explain bear here. This joke is funny because Yo Mama is so dumb, she doesn't know the difference between a football team called the Rams and actual ram animals. You know, the ones with the curly horns that go "baa." It's funny because it makes fun of Yo Mama's lack of smarts, which is a common theme in Yo Mama jokes. Also, you are probably very stupid too.