Students arrive Saturday evening for the Hockinson High prom.

CLARK COUNTY, Wash. - Prom season is underway, and it comes with a crackdown on simulated sex on the dance floor for one school in southwest Washington.

For Hockinson High School's senior prom, you needed more than a ticket to get in. You needed a contract or letter signed by both kids and their parents promising that there won't be any "inappropriate dancing" at the prom.

Some call it grinding. Others call it freak dancing. It basically amounts to two or more people rubbing their bodies against each other in a sexually suggestive manner.

Hockinson High Principal Sandra Yager said the idea for the contract came from a student who needed her signature on a similar contract so he could attend another Clark County school's prom.

"So we are not the originators of the idea," Yager said. "Even though we did think it was clear, it made every party aware of what the expectations were, and the parents, so the parents know what the expectations are for their kids."

There are about 300 kids in the junior and senior classes at Hockinson and 278 tickets sold for the prom. But just because most of them showed up, not all liked the contract idea.

"I just didn't like the idea that our parents had to sign it," said student Analisa Arnold. "I think it's like more of a personal responsibility. And I don't think any parents should have to get involved in that."

Student Kevin Ekleberry was not in favor of it either. "It was really lame," he said. "Because last year we didn't need a permission slip to go to the prom."

"I'll sign it, whatever," another student said. "It doesn't influence my behavior."

Others had more positive things to say.

"I like it," said student Katelynn Stark. "I think having a clean, fun night is gonna be good for us. So I like it a lot."

The principal said she did not think the contract stopped any kids from wanting to attend the prom.

"To the contrary," she said, "I think they will feel safe."

She said that they want to keep having proms but also want to keep them clean and safe. If the contract helps, they will probably do it again.