A Plano police officer may face disciplinary action after a video from May shows him telling a teenage driver to stop smiling while pulled over, and later shouting an expletive at the driver and his passengers.It isn’t clear in the video why the officer, identified by Plano police as Jeff Willis, stopped the teens.The teen driver did not immediately respond to The News’ request seeking comment. He told CBS 11 that the officer pulled him over at a car meet near the Dallas North Tollway and Spring Creek Parkway and accused one of his passengers of showing him the middle finger.At the start of the video, Willis tells the driver he needs to leave and then tells him to stop smiling. thescoopblog.dallasnews.com/files/2015/08/1451325_5626544171 Jeff WillisLater, the officer tells the youngsters they’ll spend more time with him if he sees them again.“What did I do?” one of the passengers asks.“I don’t know. I just don’t like you, I just don’t like you,” the officer says.The teens start laughing, telling him: “Have a great day, officer.”The officer then responds with an expletive.“Keep going. Say something else and I’ll drag you out of the car,” he says as he walks away.Plano police spokesman David Tilley said the department launched an internal investigation soon after it was posted on Facebook.Investigators concluded today that disciplinary action should be taken against Willis, Tilley said.But, Tilley said, he couldn’t go into details because Willis can appeal the punishment.Before he joined the Plano police department in 2002, Willis was a lieutenant commander in the Navy. He was awarded the Joint Commendation medal for his military service in Cambodia, according to the Plano Police Department’s Facebook page.