Credit: Jason LaVeris/FilmMagic

Everybody cut loose at the Footloose afterparty in L.A. Monday -- even Ryan Seacrest!

The 36-year-old joined girlfriend Julianne Hough at W Los Angeles, where Seacrest surprised party guests by showing off some slick moves on the dance floor.

"It was seriously like the end of the Footloose movie. Everybody down there, including Ryan and Julianne, were foot stopping and had their hands up," a party guest tells Us Weekly. "Julianne was so happy because apparently Ryan never dances and this was the exception he made for her, because he was so happy for her."

When Us caught up with Hough, 23, at the film's Nashville premiere Thursday, she admitted that she wasn't expecting her beau to bust a move when DJ Bizzy hit the turntables.

"It's like really awkward, but really cute," she gushed of Seacrest's skills. "My brother Derek does a better impression."

The American Idol host even won raves from some of the film's stars.

"He's a very good dancer for an average-sized person," 24-year-old Miles Teller, who plays Willard Hewitt in the remake, joked Thursday.

Added star Kenny Wormald, 27: "He's very impressive!"