What Does the Frog Say?

A mother was reading a book about animals to her 3 year old daughter:

Mother: "What does the cow say?"

Child: "Moooo!"

Mother: "Great! What does the cat say?"

Child: "Meow."

Mother: "Oh, you're so smart! What does the frog say?"

And this wide-eyed little 3 year old looked up at her mother and replied, "Bud."