Caution — road twerk ahead!

Two passionate passengers hopped atop the roof of a white SUV driving westbound along Interstate 64 in St. Louis on Monday, where a quick-thinking registered nurse pulled out her cellphone and recorded the wild routine.

“We were in traffic obviously and were going pretty slow, but then I saw a girl get out of the car and get on top of the vehicle,” Jackie Friedhoff told The Post early Wednesday. “And I’m like, ‘Did I just see that?’”

Friedhoff, 30, said she was only driving about 10 mph when she spotted the two women, both of whom were wildly gyrating their backsides as the GMC SUV motored down the highway. A third woman can be seen hanging out of a passenger-side window, capturing the dangerous maneuver on her cellphone.

Friedhoff said the unidentified women jumped on top of the SUV on two separate occasions, causing several other drivers to slow down and inquire about the spontaneous dance party.

“I was surprised,” Friedhoff told The Post. “It was definitely a safety concern. They’ve could’ve been blown off and hurt themselves or caused an accident.”

The SUV did not have a license plate, according to Friedhoff, who did not report the incident to St. Louis police.

“It didn’t cross my mind, I guess,” she said. “But I posted it on Facebook in hopes that they would get caught.”

Incredibly, one of the women seen in the video even reached out to Friedhoff to ask her to tag her in the video. She has since deleted her Facebook profile, Friedhoff said.

The two videos posted Monday by Friedhoff had exceeded a combined 250,000 views on Facebook as of Wednesday. She never expected the impromptu twerk session to be such a hit, she said.

“Yeah, I was honestly not expecting it to go viral,” Friedhoff said. “Normally I’m a pretty private person and I don’t post personal stuff like that, so it was odd for me to post that on Facebook.”

Friedhoff said friends are already calling her famous for putting the twerking twins on blast.

“And I’m like, ‘No, I’m not,’” she told The Post. “But I couldn’t believe what I saw.”

A St. Louis police spokeswoman, meanwhile, said no calls were received in connection with the incident.