When the person/persons in the backseat of any vehicle gets blasted by high velocity wind, be it cold or hot.
This is due the lethal combination of open windows and high speeds. The Driver is then referenced as a "douche bag", especially if it is done intentionally.
This can also be done as a deterrent for driving someone that the Driver particularly doesn't like driving around. As well the Driver reserves the right to pretend like they can't hear the person in the back seat, pleading for mercy.
"Woah! Dude put up the fucking windows, I'm getting some hardcore backseatair!"
Joe:"Man, Jake was being such a douche bag."
Gary: "Awe, pulling the old BackseatAir eh?"
Backseat Occupant: "Yo! Roll up the windows!"
Driver: "WHAT!? I CAN'T HEAR YOU!"