Young people have always been drawn to risky behavior, and the latest dangerous thrill is called "ghost riding the whip."
Ghost riding involves leaving the wheel of a moving car and walking, running, or dancing beside it.
It's a craze that's catching on, especially on the Internet, with young people making and posting hundreds of ghost-riding videos online.
Teens ghost ride on suburban roads, in parking lots, and on the freeway.
Some of the stunts are highly choreographed, with kids jumping in and out of moving cars.
One tape of a ghost-riding stunt shows a teenager wrapping up his stunt just as a school bus approaches.
Another shows a ghost rider losing control completely, his truck crashing into a fire hydrant and a utility pole.
"First thing a parent should say to their kid is, 'Don't participate in that activity,'" said Mark Helms, the assistant chief of the Stockton, Calif., police department. "It's extremely dangerous."
Ghost riding is an updated version of car surfing, which has been going on for decades and has killed young people across the country.
A group of teens from Nashville, Tenn., who made a ghost-riding tape acknowledged that it probably wasn't that smart, but that they would do it again.
"Ghost ride was started not to see people succeed, but to see people fail," Jonathan Lovecchio said. "They want to see people run into trees, run over their foot."
Ghost riding appears to have taken off as a result of popular rapper E-40, who has a song where he repeatedly chants, "Ghost ride the whip."
"Whip" is slang for car. E-40's song is the backdrop for many of the ghost-riding videos on the Web.
"We would have never done this without the song that we were playing," Lovecchio said. "If you don't play that song, you are not a ghost rider."
In cities like Stockton, officials say ghost riding is a growing problem, especially when it is part of what's called "sideshows" -- illegal group gatherings characterized by loud music and automobile acrobatics.
Sideshows have reportedly resulted in eight deaths.
"Parents need to be responsible and know what their kids are doing," Helms said. "It's very likely that your child could get hurt out there."
Stockton police say in the last four months, they've arrested 171 people and impounded 482 cars at sideshows.
Rapper E-40 and his record label, Warner Bros., had no comment when asked about the song.