An armchair quarterback is someone who criticizes the actions of the players or coaches from the comfort of their own home, without actually putting in any effort themselves. This term can also be used to describe someone who offers unsolicited advice and opinions on a subject they know very little about. Some synonyms for armchair quarterback include backseat driver, Monday morning quarterback, keyboard warrior, sideline commentator, and couch critic. These terms are often used in a humorous or sarcastic way to describe someone who thinks they know better than the experts. It's important to remember that constructive criticism is valuable, but it should always be delivered in a respectful and informed manner.