I took pride then, and have ever since, in not being a gaper.*
About an hour ago, I turned right from Rt 16 onto Rt 38 (northbound) in Medford, intending to take the quick jog to Rt. 60 by way of the rotary. After finishing my turn, I noticed that traffic approaching the rotary looked a bit snarled, the snarl probably contributed to by what I thought was a wrecked car on the back of a flatbed truck, that had somehow managed to get itself crosswise to the flow of traffic. (An obviously impossible U-turn? Turning left from some side street across the southbound lanes?) So I slowed down, and moved left (left being best IME for the ~290° turn I was planning to make around the rotary. A few cars in front of me moved, going around the snarl, some left, some right. I crawled forward perhaps another 50 feet. And suddenly realized that the car I'd thought was upside-down on the back of a flatbed that had gotten itself crosswise to traffic was in fact a car upside-down on the pavement. Simultaneous with that realization, I caught the the blinking lights in my mirror. So I made sure the way was clear, and pulled off to the right. I momentarily thought of taking out my phone and getting a picture, but then a fire truck went by, followed by several police cars and another fire truck. And once they'd passed me and there was no-one else coming, I made a U-turn back to Rt. 16, and continued home that way.
Only about the time I was crossing the Mystic did I realize that my aversion to being a gaper was so internalized that I'd failed to take what would no doubt have been some pretty interesting pictures. Which might have revealed how a car ends up on its roof in the entrance to a rotary where the traffic speed is generally pretty slow. With another car off to the side of the southbound lanes, its left-front crumpled like a steroid-abuser's beer-can.
But as I failed to photograph their fail, you'll have to settle for my word-pictures....
* There are many things that make driving in Boston a horror show, but one of the first I noticed is that radio announcers here refer to these as curiosity slow-downs. An adjective that not only fails to embarrass those who hear it applied to themselves, but ought normally to be taken as a complement.