my wife and I once had a fellow pull over up ahead of us about 100 meters. He got out and motioned for us to stop. We stopped in spite of not wanting to. It was about -10F and we were on our 12 mile each way commute. He let us know we were the first bicyclists he'd seen in the dark of Winter that he could REALLY see (we had big bright rear lights) and thanked us and simply wanted to stop and compliment us. That was a hoot. I get many more honks from pickups telling us to 'get on the bike bath you @#$@' and when that happens I just wave.