A person who believes that they are always right, and can NOT be corrected, or will not accept that they are wrong about anything
What a know-it-all that guy is incorrigible
To explain the content of a situation or to clarify a request so that people with blond hair will also be able to understand.
Speaker: "this is how a clock works"
Blond: "I don't get it"
Speaker: "it shows you what time it is. That should be deblondified enough"
Blonde: "Ok, I get it now"