Jeong’s breaking point was a scene where the deranged Chang is eating a “pinecone sandwich,” one that was cut from the aired episode. “I remember sending an email to Dan and I just said, is there a world where Chang could be more grounded, because you know, I used to be a doctor, and I’m literally eating a pinecone sandwich,” Jeong recalled. He admitted Chang may have taken things too far in season 3, but maybe the character could be brought back down to earth again. “No matter how pathetic he is, he deserves a second chance.”
So, Jeong sent showrunner Dan Harmon an email, and Harmon promised him they’d write Chang a scene where Jeong could show off his range. This scene came in the mid-season 5 episode “Analysis of Cork-Based Networking,” in which Chang pitches a theme for the midterm dance. “Bear down for midterms,” he says, but the other characters don’t get it. They’re about to move on to brainstorming more ideas, but Chang starts crying. He then gives a speech that includes “all of my email,” according to Jeong. “It was really describing just what Chang has gone through, and it moved me to tears.”
“I understand I’ve been crazy in the past,” Chang says in the episode, “but it doesn’t make it less frustrating to be dismissed like this. I don’t know if you guys see me as human anymore. I don’t know if it’s like a joke to you. Are all Asian men like a joke? A racial thing? I paid for my crimes. Underneath all the craziness, I am still a human, and I do wanna make a difference. And can you respect that? Please?” The dialogue doesn’t do the scene justice though; it’s Jeong’s performance that sells it.
Source : https://www.slashfilm.com/959956/community-gave-ken-jeong-the-best-moment-of-his-acting-career/