What does sucking the teeth mean and why is it done?

Answer 1

I've never understood why it's called "sucking teeth". There is no sucking involved! All you do is make a sound with your mouth closed. It's sounds sort of like "mmmch".

People do it when they're mad or disappointed about something.

Answer 2

only rude people do it, it means they have yuk food stuck in their teeth! they need to go to the bathroom in privacy and wash their mouth!