Other than delivering hard hits on the field for the Firebirds, Free State linebacker Keith Loneker says delivering a few lines and acting this summer in the upcoming football movie “Underdogs” was one of the coolest things he’s ever done. Pictured with Loneker is his copy of the “Underdogs” script, which was signed by the movie’s cast, including football Hall of Famer Joe Namath.

Last summer, Keith Loneker finished up all of his Free State High football responsibilities and headed to Ohio with his father, Keith, Sr.

The trip would consume two weeks of what could have been uninterrupted free time during Loneker’s break from school, which made him skeptical at first. Once he and his dad arrived at their destination, he figured out there were much worse places to spend vacation than on a movie set.

The Lonekers spent two weeks in Canton, Ohio, contributing to an upcoming football flick titled, “Underdogs.”

Keith, Sr., a former Kansas University offensive lineman known for his small acting parts in motion pictures such as “Leatherheads,” “Lakeview Terrace,” “Out of Sight” and a brief appearance in “Superbad,” drew the role of Coach Ryan Cooper. It so happened that the filmmakers could use his son, too, as one of the players on the Knights, the high school team around which the plot revolves.

When his father asked him about giving acting a try, Loneker couldn’t pass up the chance.

“Seeing him do it, I always wanted to try it,” the FSHS senior said.

“Underdogs” — which opens Aug. 16 exclusively in Ohio, at theaters in Canton, Columbus and Pickerington — had a perfect part for him, one he has played for the Firebirds each of the past two seasons: grimy linebacker.

“They let me do my own stunts,” Loneker said. “The hitting stuff, that was easy.”

Memorizing lines didn’t seem too difficult, either, because Jordan Kroger, Loneker’s character, only had a few sentences of dialogue. The tough part came when he had to act in front of the camera and crew for the first time. Loneker felt too tense, but he received some reassurance from the acting pros on set, and got over his nerves.

“Even the big-name actors hung out with us, the people who were just getting started,” he said. “Everybody was just great.”

The film stars actors such as D.B. Sweeney (“Shoeless Joe” Jackson in “Eight Men Out), William Mapother (Ethan Rom in “Lost”) and Charlie Carver (Porter Scavo on “Desperate Housewives”), but the highlight of the shoot for Loneker was sharing a scene with a Pro Football Hall of Famer who made a cameo.

“I can’t believe I’m sitting here getting a speech from Joe Namath,” Loneker remembers thinking.

The Free State linebacker left the set with an original script signed by the film’s stars, including Namath, and returned to Lawrence before the start of his junior season with a unique how-I-spent-my-vacation story to share.

“Other than playing football on Friday nights,” he said, “that’s one of the coolest things I’ve ever done.”

Still, teammates Blake Winslow and Joe Dineen said he didn’t come back bragging about it. Loneker hasn’t even asked anyone to check out the movie’s trailer, in which he appears. He fielded some good-natured jabs and occasionally got called “Big Time” or “Hollywood” by his buddies, but the Firebirds know Loneker is far more concerned about his play on the field than his acting chops.

Free State coach Bob Lisher expects Loneker to be a two-way starter this fall, and commended him for his athletic ability, toughness and leadership.

“He’s a physical player,” Lisher said, “and he wants people around him to be physical, too.”

Winslow, a fellow linebacker, said Loneker sniffs out offensive plays better than just about anyone, and his approach doesn’t drop if it’s a Tuesday and the stadium seats are vacant.

“It’s his intensity at practice,” Winslow said. “It kinds of gets us all fired up.”

Dineen, Free State’s senior quarterback, said all the Firebirds recognize how important Loneker is to the team’s success.

“He’s just another big piece of the puzzle. He’s a leader on defense and he’s gonna be great on offense,” Dineen said. “I know he can run, he can catch, and obviously he’s a great linebacker (second team All-Sunflower League in 2012).”

Personally, Loneker can’t wait for the season to start — the Firebirds open at home Sept. 6 versus Shawnee Mission North.

“I know all of us seniors, Joe, Blake, Stan (Skwarlo), everybody, we’re all ready to play,” he said. “All our juniors are on board. Everyone was working hard this summer. I was proud.”

The Firebirds hope to make a deep playoff run this fall and after that Loneker wants to play college football. He has spoken with Kansas University, and Northern Illinois invited him to attend a game this fall, but he said coaches from those and other programs want to see game footage from his senior year before extending an offer.

Once he gets to a college campus, Loneker might take some drama courses and see if acting could be a part of his future.

“I think that’s one of the routes I could take,” he said. “It’s pretty fun.”