Sweet. No, never been in a chain reaction. Barely missed one though. In Jacksonville FL I was on the highway, far left lane because up a ways there would be stop lights and I had to turn left. There was a break in the median and this little old lady who could barely see over her steering wheel managed to cross the opposite side of the highway and into the left lane of traffic right behind me. Let me say, at 70mph this was not a wise thing to do given the stream of traffic behind me. Yeah, I could see the cluster**ck in my rearview mirror.
I've had several close calls though. One nearly did me in emotionally. On a highway here in town, left lane coming up on lighted intersection. Had the green, steady traffic to my right and this minivan cuts over in front of me at the very last possible second to come to a complete stop in the middle of the intersection to try to turn left. There was still traffic in the right lane, couldn't dodge, so slammed on my brakes and barely stopped with a few inches to spare. Three kids' heads popped up in the back of that van turned around looking at me wide eyed. If those kids could have read lips they may have learned several words they shouldn't have. Went on grumbling about the person but when I got home, in the door, I broke down crying. It's amazing how we can hold it together in such situations, but the stress will come out eventually.