A stubborn, thickheaded and determined person that doesn't think things through before acting upon them.
Person 1: "You really should think before you speak you bonehead"
Person 2: "I just say what I think I don't need to censor myself"
Person 1: "You just need to realize that it might not come out the way you want it to, you could rule the world if you just took the time to clean up your ideas."
Person 2: "I don't think so I think I do just fine."
Person 1: "Well, at least I try to help but you are such a bonehead you won't accept friendly advice."