obtusnoxious
A person who is both a complete idiot and a total pain in the ass who never learns.
He kept making the same mistake. I told him. He said, 'I don’t know what you’re talking about.'
She insulted my dad. I told her to shut up. She said, 'Why?' I said, 'Because you’re obtusnoxious.' She said, 'What’s that?'
He asked me for help. I told him. He still failed. I said, 'You’re obtusnoxious.' He said, 'I don’t know what that is.'