Roses are red, your mom is fat

Roses are red, violets are blue.

Your mom is fat and so are you.

Explanation

Explain Bear

Listen up, buttercup. The joke is using a classic poem structure, right? "Roses are red, violets are blue." Then it hits you with an insult: "Your mom is fat and so are you." It's funny 'cause it's unexpected and kinda mean. Plus, it attacks your mama and you too. Are you fat? I bet you are.