BOURBONNAIS — It seemed like a routine gas-station stop on his way to Bears training camp. Right guard Kyle Long just needed essentials for the drive: ranch sunflower seeds, chewing tobacco, bottled water and a coffee.

But an unexpected item caught his attention, and he suddenly had to have it. Try to picture the clerk’s face when this grinning 6-6, 316-pound man completed his shopping trip by slapping a pack of Uno cards on the counter.

The other offensive linemen were equally bewildered when Long proudly presented his purchase in the locker room. Left tackle Charles Leno Jr. thought it was a joke. It surely was not, and Uno has consumed the offensive line during the first week of camp.

‘‘They get pretty tense,’’ right tackle Bobby Massie said. ‘‘There’s been one game going on the past three days.’’

That’s right. As the Super Bowl-or-bust Bears left a rain-soaked practice field Monday, the offensive line was itching to resume an Uno game that began Saturday. This is the type of nonsense that arises in an intensely familiar, stress-free crew. It’s a fun time to be a Bears offensive lineman.

Their continuity makes camp drudgery more enjoyable, and the Bears intend to maintain it. Four starters are signed through 2020 or beyond, and the fifth, left guard Cody Whitehair, is likely to get an extension soon.

Long was a first-round draft pick in 2013, Leno arrived the next year, Massie and Whitehair joined in 2016 and center James Daniels fit in quickly as a rookie last season. They know each other’s stories, all of which have merged to form one of the NFL’s elite lines.

‘‘He’s a seventh-rounder, came in my second year and lived in my spare guest room on a blow-up mattress,’’ Long said, nodding toward Leno nearby. ‘‘Didn’t know if he was gonna make the team. Now he’s Charles Leno, left tackle, Pro Bowler.’’

He carried on, raving about Whitehair’s and Daniels’ rapid acclimation, calling Massie his best friend and hyping Harry Hiestand as arguably ‘‘the best offensive line coach on the planet.’’ There’s a lot of love in this group, and it transfers to the field.

They have a brotherhood unlike any other position, and it comes from literally working shoulder-to-shoulder. Long is a three-time Pro Bowl selection, and Whitehair and Leno were picked last season. But talent isn’t enough on the offensive line.

‘‘It takes all five of us being on the same page for the offense to do anything,’’ Leno said. ‘‘So us vibing in training camp helps us get better.’’

Uno is part of that chemistry, and it’s no surprise this group came up with its own rules.

That seems unnecessary, considering how elaborate the original rules are, but these guys are imaginative. For example, if someone plays a Draw Four, the next player can counter with a Draw Four of his own. Then the burden of drawing all eight of those cards falls to the next man. Follow that?

Those scenarios spark some arguments because, as Massie put it, ‘‘When you’re making up your own rules, things just happen.’’

Most of the tweaks are minor, but they’re strictly enforced.

‘‘I don’t think any of us fully comprehend the actual rules,’’ Long said. ‘‘We’ve made some subtle changes. [Leno] confirms all the rules. He’s the left tackle. They’re supposed to be in charge of everything.’’

Most of that officiating involves one particular teammate.

‘‘Trust me, there’s a lot of cheating going on from Cody Whitehair,’’ Leno said.

Leno couldn’t have fathomed being in charge of anything the first time he pulled into Bourbonnais. He was the 246th pick of the 2014 draft, just trying to survive. His growth since then parallels that of the offensive line overall, and now that unit is the strongest aspect of the Bears’ offense.

‘‘It’s real tight-knit, kind like a wolf pack,’’ Leno said. ‘‘It’s really fun going to work with these guys.’’