English Daily Workout: Personality Idioms: an armchair critic

Personality Idioms: an armchair critic

An armchair critic is some  who expresses opinions about things they know very little about.

Example:

"I am fed up with John's criticism about my work. He sits there watching T.V. all day long and thinks he has the right to tell me how to do my work. He's such an armchair critic. I bet he can't do half of the things I do"