Liz Dahl of Sacramento and her son were headed home on Interstate 80 from an Oakland A's game when a red Camaro sped by, weaving in and out of traffic.
Then came another Camaro, then another, all weaving from lane to lane.
Suddenly, one of the Camaros went into a spin, essentially doing a donut at freeway speed.
Did the driver accidentally lose control? Doubtful.
A passenger in one of the Camaros was leaning out a window shooting video of the spinning car.
Dahl and her son were left shaken, and wondering: Is this something the drivers were doing to post videos on YouTube or Facebook?
The very risky and very illegal stunt is an extreme case of a type of driving some call "hooning."
It isn't new. Car fans have long gathered to film themselves doing burnouts, skids, donuts and other stunts. Often, they do it in the somewhat safe confines of empty parking lots.
YouTube offers a way to get those videos out and seen by thrill watchers the world over.
But the idea of doing something this wild in traffic on a major freeway, that's seriously bad news. We checked with the California Highway Patrol in the Bay Area and Sacramento, and officials say they think it's rare. They do ask that other drivers call them immediately to alert them if they see such driving.
Oakland CHP spokesman Sam Morgan said his agency has used YouTube videos as evidence in reckless driving cases.
The incident Dahl saw occurred not long after a popular video hit YouTube showing a professional stunt driver named Ken Block thrill-driving a few miles away on the Bay Bridge and on San Francisco streets.
Near the end of Block's video, he steers his car into a smoke-spewing spinout on the Bay Bridge.
What's notable about the video: There are no other cars on the bridge or any of the streets he uses.
Block, who was filming a commercial sponsored by a shoe company, got permits from the state and city to do the stunts. San Francisco officials blocked off city streets.
In the case of the Bay Bridge, filming took place early on a weekend morning, and CHP officers briefly slowed traffic to keep it back and away from the stunt driver, according to state and S.F. film commission officials.
We found it interesting that authorities would agree to offer up their streets for a video that glamorizes dangerous driving.
"We don't encourage anyone to try this; it's not safe," S.F. police Sgt. Michael Andraychak said.
We couldn't get a comment from the state Department of Transportation or the CHP. A few months ago, however, a CHP spokesman told the San Francisco Chronicle:
"They pay, so we let them do whatever they want as long as it's within the permit."