|First appearance:||High Top Fade-Out|
|Last appearance:||High Top Fade-Out|
Joon is a college friend of Burton "Gus" Guster, Tony Clemon and Leonard "Diddle" Callahan, and 1/4 of the original Blackapella group. Blackapella broke up when they were in college due to girl trouble, but after Diddle's murder they got back together along with Shawn Spencer and Tony's brother Drake. Joon is portrayed by Kenan Thompson.
In "High Top Fade-Out", Joon is with Tony at their old friend Diddle's funeral. They sing "Swing Low, Sweet Chariot", but afterwards ignore each other, as Gus reveals to Shawn that they broke up in college and he doesn't want Shawn to get involved. However, Tony and Joon ask Shawn if they can hire him to investigate Diddle's death, as the police has ruled it an accident, however they believe it to have been a murder. Shawn agrees, much to Gus's chagrin. All three of the remaining members of Blackapella reveal they all recieved the same encrypted email entitled "It's So Hard to Say Goodbye..." from Diddle the day he died. Joon, Tony, Gus and Shawn investigate Diddle's apartment, where they find their old band jackets. They put them on and dance a little, before remembering they're feuding and going back to their bad blood. Their Shawn discovers clues that leads them to believe Diddle was murdered.
After Shawn and Gus figure out that Diddle was, in fact, murdered, they tell Tony and Joon that the killers may know about the email, and they could be in danger as well. Joon and Tony begin to say that they don't know about the email and try to get away, but when Joon unlocks his car it explodes. After Shawn and Gus get back from Diddle's old employer CyberVault, they go to Henry's where they left Tony and Joon. While there, a woman Shawn and Gus met at CyberVault named Chelsea calls, and Tony and Joon said Gus will always sell out his friends for a girl, which is why they broke up. Gus says that they slept with his girlfriend, which is why they broke up, but they insist she was a groupie. Gus storms out, with Shawn following and telling them not to follow.
When Shawn and Gus get to their location, a warehouse, they discover Joon and Tony followed them, but they get kidnapped. When Shawn & Gus accidentally blow an undercover operation of a man they saw at Diddle's funeral, Detective Moses Johnson, and that he'd taken Joon & Tony under police protection, and they're safe. The four are reunited, and are happy to be back together, and make up. Shawn figures out the encryption is a quartet singing, "It's So Hard to Say Goodbye to Yesterday" by Boyz II Men, and the encryption reveals Chelsea was the rat that gave the drug dealers CyberVault information.
Afterwards, Shawn officially joins Blackapella, and suggests they change the name to "Quarterblack". Joon likes this idea saying 'It's like we're all Randall Cunninghams'.
Joon chose not to come to the fundraiser, despite Shawn, Gus, Tony, and Drake changing their schedules to accommodate him.