Old Cowbelle: Cars
When I was in grade school (waaaaay back), the greatest rivalry among students was what kind of car their parents drove. Mostly Ford or Chevrolet. Very few people in the neighborhood had "big cars" like Oldsmobile, Buick, Chrysler...and no one owned a Cadillac.
Most of our relatives owned Fords and the Chevy people would call them "tin cans," etc. I don't remember what our comeback was. How silly!