The grainy high school dance video is lurid.
A teenage boy dances behind his winter-formal date, hands on her hips, thrusting his pelvis against her while she hitches up her satiny gown and bends at the waist. Another couple dance facing each other, their bodies enmeshed and their hips gyrating in a frenzy. A boy approaches a third couple, nearly sandwiching the girl between himself and her partner.
Teenagers call it "freaking," a style of dance made popular on MTV. Educators call it "simulated sex" that has no place at school dances. This clash between outraged adults and sexualized teens is being played out at homecoming dances, winter formals and proms across the nation, most recently at Aliso Niguel High School in Aliso Viejo.
After a jungle-themed dance in September, Principal Charles Salter canceled all future dances until students, parents and administrators craft a plan to stop freak dancing.
For months he'd implored parents to get their children to stop freaking, and even showed a video of the school dance to hundreds of parents at back-to-school night.
"The 'dancing' of our youngsters today is one step from events that should be occurring on wedding nights," he wrote in an e-mail to parents.
Though forms of freak dancing -- also called "grinding" or "the nasty" -- first appeared years ago, so many students are doing it now that educators nationwide are drawing up rules of behavior, changing music formats away from freak-friendly hip-hop, and banning from dances students whose movements are deemed too sexual.
"Of all the things that happen at a high school, having to spend so much time on dances -- that's out of whack," said Kelly Godfrey, principal of Los Alamitos High School in Orange County.
Some students say a crackdown on freaking would discourage them from attending school dances.
"I wouldn't go," said Chelsea Walsh, 15, a sophomore at Aliso Niguel High. "It would be boring. How else do you dance?"
When the waltz was first performed at a royal British ball in 1816, the Times of London wrote: "So long as this obscene display was confined to prostitutes and adulteresses, we did not think it deserving of notice; but now that it is attempted to be forced on the respectable classes of society ... we feel it a duty to warn every parent against exposing his daughter to so fatal a contagion."
Similar generational clashes over the tango, the twist and Elvis Presley's gyrating hips followed; the theme was celebrated in the 1984 movie "Footloose."
Freaking has gained widespread acceptance in recent years, propelled by the mainstreaming of rap music and the sultry images in hip-hop videos. Critics say its unquestionably carnal positions -- girl bent at the waist, boy thrusting behind her -- go far beyond previous generations' bumping and grinding.
"Every generation finds its successors' dances to be improprieties," said Judith Lynne Hanna, a University of Maryland senior scholar and author of a book on dance and sexuality.
"What is the difference between frontal body rubbing and one person rubbing a backside against a front side?" she asked. "It's all sexy. Dancing is sexy. But so what? It's not sex. It's flirtation."
Whatever it is, educators from New Hampshire to Washington state are growing increasingly agitated.
Shana Kemp, spokeswoman for the National Assn. of Secondary School Principals in Reston, Va., said the organization had received an unusually high number of calls in recent months about freak dancing.
"Each generation has its own thing that ... adults think is inappropriate. It's just par for the course for the changing of the times," she said. "But in some instances, it's taken too far."
Just this month, Principal Patricia Law canceled all school dances at Windsor High School north of Santa Rosa for the rest of the year after a homecoming dance where three-quarters of the nearly 800 students in attendance were freak dancing. She said students can win back their dances if they come up with a plan to keep their moves clean.
"It was time for a wake-up call," Law said.
At Wethersfield High School outside of Hartford, Conn., Principal Thomas Moore said he'd grown increasingly concerned as more students started freak dancing. Last year, he estimated, three-quarters of the student body were freaking.
Student council members launched their own campaign, "Freeze the Freak," visiting social-studies classes where they led student-only discussions about the issue.
Moore also regularly turns on the lights during dances and changed the music format at September's back-to-school dance.
"We went with a lot of wedding music, like the 'Macarena' and the 'Electric Slide,' to get away from some of the real bass-thumping club music," he said. "A lot of kids had fun with it. A lot of kids left."
Several California schools have adopted detailed dance policies and kick out students who repeatedly cross the line.