A native Aboriginal word from Australia tat literally means a nutty chatter or a person who talks a lot but has empty thoughts of what he/she is talking about.
Someone who is forcing his/herself into a conversation even without knowing the issue or topic. It can also be someone who tries very hard to speak a language he/she doesn't know well thus causing the idea be rumbled and confusing the receiver.
Stop being a chatnut.
That chatnut caused the spreading of wrong information.
You're a very annoying chatnut.