It is idiom and means that it is totally useless.
Also used “as useful as a chocolate fireguard”
- A car in a heavy traffic jam is as useful as a chocolate teapot.
- That umbrella is stuck inside out, so it’s about as useful as a chocolate teapot right now.
- If the referee gives the opponents a penalty, he yells, ‘When they circumcised you they threw away the wrong part.’ If a player is not trying hard enough, he bellows, ‘You are as much use as a chocolate teapot.’