A backseat driver is someone who gives unwanted advice or criticism while riding in the REAR of a vehicle. A BUSYBODY is someone who meddles in other people's affairs, an ADVISOR is someone who gives advice, a NAG is someone who constantly complains, and a CRITIC is someone who evaluates or judges something. Rides refers to the act of being a passenger in a vehicle. All of these terms can be used to describe a backseat driver.