First off, let’s just admit that it was a bad joke. Terrible, really. More of a groaner than a knee-slapper. And if you weren’t paying attention, you might have missed it.

That’d be a shame, since the joke, awful though it was, served a purpose.

It started with Cub Swanson (24-7 MMA, 9-3 UFC) on the stool after the first round of his fight with Dooho Choi (14-2 MMA, 3-1 UFC) at UFC 206. The two featherweights had already mixed it up pretty good and were about to pick up the pace considerably in the next frame, but first Swanson’s longtime coach Greg Jackson had a question for his fighter.

“Do you remember that fish that ran into a wall?” Jackson asked.

For a split-second, Swanson seemed as lost as the rest of us. Then he snapped to it.

“Did he say, ‘Oh dam?’ Swanson replied.

“He did!” Jackson said. “You’re on tonight.”

It was brief and bizarre enough that it almost escaped notice on the pay-per-view broadcast. UFC commentators Joe Rogan and Mike Goldberg seemed to realize that Jackson had said something about a fish, and that it seemed pretty weird, given the context, but that’s about it.

Look closer, though. There’s more going on here than just Jackson goofing around. After all, this wasn’t really him telling Swanson a joke. This was him asking Swanson to fill in the punchline. It was a mid-fight exam, a little cognitive test devised by one of the most successful trainers in the sport.

Jackson confirmed as much on Monday when I reached out to ask him about the moment.

“Yes, I wanted to make sure his mind was still moving so that I could adjust my coaching accordingly,” Jackson told MMAjunkie.

He added that it was reference to an old joke he’d told Swanson in an earlier fight, something he knew his fighter would remember under normal circumstances, which aren’t always what you find yourself in once the fists start flying.

“He answered correctly,” Jackson said. “So I knew he was still in it.”

Of course, moments after Swanson got off the stool and got back in the fight, that’s when things really kicked up a notch. Early in the second he dropped and nearly finished Choi. In the corner audio from the fight, you can hear Swanson’s other coaches imploring him to finish.

“He’s hurt!” they shout. “Put him away!”

Then you hear Jackson’s voice chime in with a different message: “Discipline!”

The way Jackson told it, that was a particular concern for this very fight. When Swanson sensed a finish might be close, he got wild. He went after Choi with a wide-open attack that left him vulnerable, and Jackson worried that if his coaches got carried away, so too would Swanson.

Or, as he put it to his fellow coaches in the heat of the moment: “He could knock Cub out!” Here followed a choice expletive to drive the point home.

Choi also made the same point seconds later, as he fired back and, even in his woozy state, nearly succeeded in putting Swanson on the floor. Then a more disciplined approach really started to sound like a good idea.

Ultimately, it was that violent seesaw in the action that helped make the fight what it was, which is a near-certain candidate for “Fight of the Year.” It was also a spectacular win for Swanson, and he earned it in part by keeping calm under fire.

The “Korean Superboy” had youth and power and an almost superhuman ability to take a punch. But Swanson had veteran savvy and years of experience, and that mattered down the stretch.

Plus, anyone who can remember Jackson’s bad jokes during a fight is obviously pretty cool under pressure. And, if he actually appreciates them, he’s probably also pretty rare.

And for complete coverage of UFC 206, check out the UFC Events section of MMAjunkie.