What does fan dabby dozy mean?

Fan dabby dozy is an archaic expression that means "extremely foolish or stupid." It is now most commonly used in the United Kingdom, where it is often used in a humorous or light-hearted way. The word "fan" in this phrase is thought to be a corruption of the word "fang," which was used in Old English to mean "to seize" or "to catch." The word "dabby" is thought to be a corruption of the word "daft," which means "stupid" or "crazy." The word "dozy" is thought to be a corruption of the word "drowsy," which means "sleepy" or "lethargic."