Barrett is a five-time Intercontinental Champion and former King of the Ring winner. He now works in NXT as a commentator.
During an appearance on Inside The Ropes in 2019, Barrett explained how he had only seen Lesnar once in the gym during his time on the road and how the atmosphere changed when he walked in.
"Just as we were about to finish up, Brock walks into the gym," he recalled.
"I've never seen him walk into a gym before, and everyone working out in the gym stops what they're doing -- but I'm not talking about the wrestlers here, I'm talking about all these other people here packed out in this Gold's Gym -- they just stop what they're doing and they stare at this animal who's just walked in. 'What is that?!'"
According to Barrett, Lesnar revealed to his fellow wrestlers in the changing area that a stalking fan had followed him around every machine before heading off to the toilet area.
And Barrett, real name Stuart Bennett, said the 16-year-old decided to follow the 'Beast' into the toilets before he bolted out of the area after the ex-UFC superstar angrily asked him if he "was trying to see my f*****g penis?"
He explained: "Anyway, we're finishing up and then suddenly, this nervous sixteen-year-old nerdy kid pops his head around the locker room.
"Sometimes we get that and people are excited because they've seen us on TV and we're wrestlers for WWE -- and they want to meet us.
"This kid did not care about us at all, it was like we were invisible.
"He's sneaking around, he's looking past us and then, suddenly, he spots the toilet area which was just around the corner from where we're at.
"This kid kind of stumbles past walks around the corner and disappears. A small part of me wanted to tell this kid, 'No, this isn't the day.'
"But another part of my brain thought, 'Ya know, the boy has to learn.' So I didn't say anything; I just kind of looked at Bray Wyatt and he kind of shrugged his shoulders.
"We all knew that something bad was about to happen. We were just waiting; we were frozen in time. Suddenly, all you hear is, 'Are you trying to see my f*****g penis?!'
"Followed by this terrified sixteen-year-old running out of there, through the door, never to be seen again."
Barrett felt sympathetic towards the fan for wanting to feel the "aura of Brock Lesnar," but he couldn't help but see the funny side of the incident.
He said: "Now, I kind of guess what happened here was this kid -- nobody intentionally tries to see Brock's penis. But this kid was sixteen years old [and], for him, Superman had just walked in there.
"He just wanted to absorb the aura of Brock Lesnar and experience what it was like to be in the same room as him.
"And he was just overcome, overwhelmed by this monster of a man being around him.
"He just wanted to be as close to him as he could in some way.
"But the thing that always makes me laugh about the situation was Brock, in his anger, 'Are you trying to see my f*****g penis?'"
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