Arrange a set of chairs as you would find seats in a car. Four seats should probably be the minimum, yet this game will seat six comfortably.
Seat all but one of your players, as a driver and passengers, while leaving one passenger seat open.
Pick up one player as a hitchhiker. This hitchhiker will exhibit a quirk of personality or behavior, anywhere from being a drunk to giving birth to being a deaf rock guitarist.
Have the other players in the car take on the same personality as the hitchhiker, in their own way.
Play to your heart's content, generally for several seconds or up to a minute.
Have the driver make up an excuse to exit the vehicle. Rearrange the remaining passengers to the same seating configuration as in Step 2, so as to leave one passenger seat open.
Pick up a new hitchhiker, who will exhibit a new and unique quirk.