A woman gets on a bus with her baby. The bus driver says: “That’s the ugliest baby that I’ve ever seen. Ugh!” The woman goes to the rear of the bus and sits down, fuming. She says to a man next to her: “The driver just insulted me!” The man says: “You go right up there and tell him off – go ahead, I’ll hold your monkey for you.”

Source: http://en.wikipedia.org/wiki/World%27s_funniest_joke