On his first carry wearing a Kentucky jersey in front of fans, the "BOOOOOM!" rang out.
Offensive coordinator Neal Brown just shook his head.
"Stanley. Stanley," Brown corrected in his post-Fan Day huddle with reporters when asked about true freshman Stanley Williams and the Commonwealth Stadium chorus. "You've got to earn Boom around here."
"Boom" was a nickname Williams more than earned while in high school in Georgia, where he was a four-star speedster with offers from big names like Auburn, Clemson, Georgia, Louisiana State and South Carolina among others.
Sign Up and Save
Get six months of free digital access to the Lexington Herald-Leader
Heck, even his mom calls him "Boom" from time to time.
"When it comes to football and I'm on the field, and things like that, she calls me 'Boom,'" the running back said on Media Day. "She likes the name as well."
But not Brown.
Early in camp, the offensive coordinator tried to downplay big talk about Williams, who drew "oohs and ahhs" from fans with his speed on the perimeter in several open practices.
"What I told him, what I tried to explain to him, he broke one to the outside, that was against the (second string)," Brown told the media afterward.
"If it was against the ones, he would have got ran down. So just trying to explain to him, you're not going to outrun everybody."
Less than two weeks into camp, even Brown can't deny there's a bit of "Boom" to his 5-foot-9, 200-pound running back.
"He had a couple 'Boom' moments the other day," the offensive coordinator conceded Friday.
Can Williams earn "Boom" in practice or does he have to prove it on the field in games?
"You can earn Boom in practice," Brown said. "You get a little more street cred with me in practice probably."
As camp has continued, Williams seems to have erased any doubt that he might need a season to be a difference-maker. Even in a crowded backfield that contains Jojo Kemp, Braylon Heard and Josh Clemons, Williams stands out.
"He's done enough to earn the 'Boom' with me," running backs coach Chad Scott said. "There ain't no doubt."
Given just a sliver of space, Williams was able to get to the outside in open practices and gain huge chunks of yards as his new head coach predicted on signing day in February.
"Boom is a guy that changes the scoreboard," Mark Stoops said after signing Williams, who ran for 1,416 yards and 21 touchdowns as a senior. "That's the type of guy that can make people miss, that can put some points on the board."
His speed is the reason.
"He plays at a different gear," Brown said. "He's the fastest guy we have back there. The good thing about him is he goes from zero to full speed really fast."
Scott explained some of Brown's initial problem with Williams was normal growing pains seen with some freshmen.
"He wasn't doing the little things, which was leading to poor attitude and some poor practice habits," Scott said. "Early on he was a question mark, but he's been locked in lately."
Williams said he's been working hard to get ready.
"I'm in the film room almost every day watching film, picking up on everything," he said. "I'm trying to get everything down so I will be ready for game one."
But has he done enough to start the paperwork for the official name change with Brown yet?
Maybe. Maybe not.
But Williams seems willing to keep working on it.
"I'm up to the challenge of making plays so I can earn my name here in Kentucky."
The 2,000 barrier
As a team, Kentucky hasn't rushed for 2,000 or more yards since 2010. That's far too long, running backs coach Chad Scott said Friday as he discussed his running backs.
Scott anticipates UK breaking through that 2,000-yard barrier this season.
"We've got the kind of talent," he said. "With the opportunities we've been given and we will get moving forward, there's no reason why we shouldn't with the talent we've got."
Something that's said in nearly every running backs meeting is "Don't be a liability." Scott wants the players to be able to do all things well: run the ball, catch the ball and pick up the blitz, not to mention some specialty plays.
He thinks all of his veteran running backs like Jojo Kemp, Braylon Heard and Josh Clemons are close. Newcomers Mikel Horton and Stanley "Boom" Williams are moving in that direction, too.
"Last year, certain guys would do certain things better and it was tough just trying to get all those guys in the game at the right time," Scott said. "But now I think we have three legitimate guys who are not a liability. They can do all of it.
"We just have to keep those guys healthy and we've got young guys that we have to find a way to get balls to. We have three legitimate guys who are not a liability. Whatever play Coach Brown calls, they can go out and execute it at a high level."