Calipari levied a double punishment, forbidding him from using Twitter and putting the 6-foot-10, 275-pound center through extra running and conditioning drills for 30 minutes before practice every day, telling him: "Then you are going to practice, or you can quit."
Maybe Calipari wanted him to quit, but Harrellson saw a last-chance opportunity to improve himself as a player. He handled the 30 days, then 60, then 90. The results have been eye-popping, and Harrellson is a key reason why the Wildcats have made the Final Four for the first time since 1998 and will play Saturday in Houston against Connecticut.
In seven postseason games, three in the SEC tournament and four in the NCAAs, Harrellson is averaging 12.9 points - double his regular-season average of 6.4 - and 8.7 rebounds while shooting better than 70 percent from the field.
On Friday, he played Ohio State freshman Jared Sullinger, arguably the best big man in college basketball, to a near standstill in Kentucky's 62-60 win. He followed two days later with 12 points, 8 rebounds, and 4 assists in the Wildcats' East Regional championship victory over North Carolina.
Harrellson now calls the Twitter post "the dumbest smartest thing I've ever done."
"I just tried to change the approach," said Harrellson, who hails from St. Charles, Mo. "I changed my confidence level, changed my skill set, changed my body. I never thought that I would be the player that I am today. It is a lot of hard work and a lot of determination to push through what I have been through."
Calipari said Harrellson has gone from being "the jokester, the prankster in practice, to a guy that comes early and trains for 30 minutes before we start.
"Then he works his butt off and encourages his team to work," he said. "He has totally changed his body. He totally changed his approach to practice . . . his skill level. What's happened is you see a different result."
The timing of Harrellson's transformation couldn't have been better after the NCAA ruled freshman sensation Enes Kanter permanently ineligible last November for accepting benefits while he played for a club basketball team in Turkey.
Harrellson, who only started playing basketball as a high school freshman, spent one year at Southwest Illinois College before heading to Kentucky. During his junior season, Calipari's first year, he played only 88 minutes in 22 games and logged just 12 minutes in SEC play.
So given Harrellson's history coming into this season, it was no surprise that the Wildcat faithful uttered a collective "oh-oh" after Kanter was ruled out. But not now.
"After Enes was ruled ineligible and the Twitter incident, I wanted to be there for my teammates," Harrellson said. "I knew they needed a big man. We didn't really have a big man, and we didn't know who it was going to be. I wanted to step into the role and take it and be there for my teammates, show significant minutes, lead by example, and just show them the way to go."
Harrellson is the oldest player in Kentucky's six-man rotation that includes freshmen Brandon Knight, Terrence Jones, and Doron Lamb and juniors DeAndre Liggins and Darius Miller.
"Josh is a big part of the team," Miller said. "He has come a long way. He has done a great job of stepping up and being even more of a leader. He does a lot of the stuff that isn't mentioned. He does a lot of the dirty work."
Harrellson still has a goofy side. His teammates refer to him as "Jorts," a reference to his fondness for wearing knee-length jean shorts.
But there's nothing funny about his commitment to helping the Wildcats. Calipari is a believer.
"Look, here's what this comes down to for me," he said after the North Carolina win. "Josh Harrellson, are you kidding me? Forget we're going to a Final Four. So what? Look what's happened for him."
"Hopefully a lot of people will look and see what I've done and see my story, a lot of hard work and dedication, a lot of perseverance, a lot of patience," Harrellson said. "God presented me with a chance to come out and take the opportunity, and I took full control of it. I can't be more thankful."
Contact staff writer Joe Juliano at 215-854-4494 or email@example.com.