Before she spotted the sign-up sheet, Lindsey McAlonan didn’t even know what a flash mob was.

If they didn’t before, the 16,300 fans who packed into Allen Fieldhouse for the Kansas-Missouri basketball game Monday have a much better idea of what it is, too.

After the under-8-minute media timeout in the first half, about 150 students — with no warning — began standing up and waving their arms in the air and dancing a synchronized, scripted routine.

They all wore the same red shirt promoting Kansas University’s Buddy System, a student health and safety campaign.

“People were just like, ‘What is going on?'” McAlonan said. “Once they figured it out, everybody just started cheering us on.”

McAlonan, a KU freshman from Victoria, saw the sign-in sheet for people camping in Allen Fieldhouse for basketball seats. She zipped off to YouTube, pulled up some videos and got the general idea of what was being planned.

She added her name to the list and went to a couple of practices last week.

Cathy Jarzemkoski, KU’s spirit squad coordinator, choreographed the dance routine. It was designed to be simple and visual. She was impressed with how quickly everyone seemed to pick it up.

“When we started on Monday, everyone picked it up in like an hour,” she said. “We came back on Thursday and had another rehearsal and they knew it.”

All told, the students practiced for about two and a half hours, McAlonan said.

Frank DeSalvo, associate vice provost for student success, helps oversee the Jayhawk Buddy System. He said the idea came from the campaign’s student advisory board.

The buddy system encourages students to pair up when going out in the hopes that their peers will keep them safe and discourage them from participating in bad behaviors, like excessive drinking.

The best part about the flash mob was the makeup of the group, DeSalvo said. Though organized by student leaders and athletics officials, most of the students who participated weren’t part of either group.

“We had just general students who got to do something really cool” and get on national TV, he said.

McAlonan thought it was cool, too. She hopes flash mobs become a tradition at KU.

“I would definitely do it again,” she said.