I don't know if all kids do this or just ones raised in West Virginia. "Curves" is a game you play when you are riding along in the car and everytime you go around a curve you lean as hard as you can into the sibling beside you - effectively squashing them!
We loved this game. At least my brother and I did. It seems to me that my little sister always ended up in tears and then we would get in trouble and have to quit playing. Until she would try to get even and start the game over again.
It worked best with a full back seat (there were 3 of us) Of course now everybody is in seatbelts so I guess this game goes in the annals of history along with prank phone calls and the like.