idiom: backseat driver

xyin77

Definition: a backseat driver is commonly defined as someone who offers a
LOT of advice that you don't need nor ask for
  Example: I don't want any backseat drivers in my car. When I drive, I don't
want any advice on the route, which lane is better, and so on and so forth.
Is that clear to everybody?
  Origin: It came from driving, as you can guess. A backseat driver
originally means someone sitting in the back that constantly criticize your
driving or offers what s/he thought were helpful suggestions. \"Signal
earlier next time.\" \"Keep it under 55 MPH.\" \"Let that guy pass you.\" blah
blah blah blah. Later it came to mean any one who comments too much.