A backseat DUI occurres when a sober
person is driving an intoxicated
person home, and the intoxicated individual is giving the driver shitty directions, and false instructions to turn, and then saying "No, No, not this street..."
This causes the driver to
speed up, slow down, and begin to turn, then swerve back into the driving lane, leading others observing the vehicle from the outside to believe that the driver is DUI.