Glad you asked - What's an "armchair quarterback"?

An "armchair quarterback" is someone watching a football game in a comfy La-Z-boy-like chair with nice armrests who criticizes and second-guesses what's going on during the game.

Another common term for such a fan is a "Monday morning quarterback." Since NFL games are on Sunday, these fans analyze the games (typically bad mouthing various decisions made during the game) on Monday morning.

The terms have a hint of irony because most armchair or Monday morning quarterbacks are lugs who can only throw out the trash, yet they find it perfectly acceptable to lambaste a pro quarterback for throwing too many incomplete passes.

But therein lies the beauty of being a fan I suppose. Just don't get me started on fantasy leaguers...