My children have picked up this game, I assume from friends at school. They call a yellow car a "rubber ducky" - first one to spot and call it gets credit for it. It's just like calling a car with only one working headlight a "popeye" and calling a VW bug a "slug bug."
I'm in northern Nevada. Has this game popped up anywhere else?
I've never heard of the rubber ducky game. I'm originally from Western PA and we called a car with one working headlight a "padiddle." The VW was a "punch bug."
I grew up in WI (hi Jackie!) and for us, a car with one headlight was a "cyclops." Never heard either "rubber ducky" or "slug bug." But we had this game where, if you saw a package for Lucky Strike cigarettes on the ground, and were the first to spot it and stamp on it and call out "lucky strike," you were entitled to slug your companion in the shoulder ... typical adolescent male game.