A Utah father is speaking out against the dangerous trend of car surfing.
Kevin Kener's daughter, Sydney, was seriously injured last month after trying the stunt.
The 13-year-old rode on the outside of a vehicle while a friend drove.
She fell off and suffered severe trauma to the head.
Doctors put her in a medically-induced a coma.
Kener says, "Don't even think about this activity, the torture and pain we went through for 2 weeks. All you kids, it's not funny."
The teen survived, but will spend months in rehab.
Federal health officials say there were 99 reports of car surfing between 1990 and 2008.
And, more than half of those were deadly.