SAN DIEGO – An undrafted rookie sloppily worked through a pass-rush drill during training camp as stoic San Diego Chargers defensive line coach Don Johnson looked on, his expression hidden behind wrap-around sunglasses.

“Oh, hell no!” screamed Johnson. “You messin’ up my drill. Get back here and do that again!”

Johnson has little patience for players performing his everyday fundamental work the wrong way.

“There’s teaching moments, and then there’s moments where you have to discipline them verbally -- or have them do something over again just to get it in their mind that’s not acceptable,” he said.

A strict disciplinarian, Johnson’s no-nonsense approach earned him a nickname at Chargers Park – Don Hector Salamanca, the infirmed patriarch of a Mexican drug cartel in the “Breaking Bad” TV series.

“They have that same look,” said defensive lineman Ricardo Mathews, who gave Johnson the nickname when he joined the Chargers last season. “Like when you know you’re getting on DJ’s nerves, he has that look like, ‘I’m going to kick your ass.’”

San Diego Chargers assistant coach Don Johnson is in his sixth season coaching the defensive line. Jack Dempsey/AP

Johnson said he’s unaware of the nickname.

“They call me several things, most of them not to my face,” Johnson said, smiling. “We try to have some fun at times. But they need to know, ‘Hey, shut it down. It’s time to go to work.’”

While not an avid watcher of “Breaking Bad,” Johnson does have a link to Hollywood. He served as an extra in television shows such as "The Misadventures of Sheriff Lobo," "Matt Houston" and "Fantasy Island."

Johnson said he also appeared in a commercial for Sizzler called “Dem Bones,” hawking beef ribs.

“There were a lot of guys with indigestion that night,” Johnson joked.

Johnson lived in the Los Angeles area for several years in the 1970s and 1980s, working as a teacher at Santa Ana Valley High and Riverside Community College. Raised in a military family, both of Johnson’s parents served in the Air Force. But his grandmother was the one who kept him in line.

“She was tougher than both of them,” Johnson said.

Johnson grew up in Newark, New Jersey, and played outside linebacker at Jersey City State. He later had a tryout with the New York Jets and played for the USFL’s New Jersey Generals before pursuing a career in coaching.

“He’s a Jersey guy, so we’ve got that in common,” nose tackle Sean Lissemore said. “Sometimes when he gets in a bad mood that Jersey comes out of him -- just like it does with me -- so I can definitely relate to him on that.”

Johnson is in his sixth season coaching the defensive line for the Chargers. Top defensive lineman Corey Liuget credited Johnson for his development over the past five years, which led to the organization signing the former Illinois standout to a six-year, $58.2 million contract extension during training camp.

“He helped grow me from a college player to a pro,” Liuget said. “He taught me how to work each and every day. And when you do that, you get rewarded.”

Added Mathews: “He knows how to coach his players. He knows how to talk to us. He demands respect, and he gives it at the same time. So it’s real enjoyable playing with a bunch of guys like that and playing for a coach like DJ.”