The California Highway Patrol is investigating a man who was filmed car surfing along the 15 freeway in Corona.
The video was recorded by Jennifer Driscoll-Frerichs shows an unidentified man hanging on the side of a pick up truck.
"I was just cruising down the freeway with my husband and I saw someone start to get out of the window. He made it all the way out and was dancing on the side of the car."
She says traffic was slow, going only about 10-15 mph but quickly picked up.
It was only after the car sped up did the man get back inside the vehicle.
Driscoll-Frerichs posted the now viral clip to social media to warn people to not pull a stunt like this.
"He could've fallen, and you know, got really hurt and then caused more accidents around. It could've been really dangerous."
Other witnesses say no one did get hurt, but the CHP is asking anyone with information about the incident to call them and make a report.