Which TOS episode was this?

Correct, episode 109. It was actually Kirk's first appearance on Car Talk. You can tell he didn't do much open mic banter before this from how awkwardly he answers a lot the questions. Many fans find it to be one of the more relatable episodes, especially the part where he breaks down and talks real about his brother. As funny and meme-worthy the later Car Talk episodes with Kirk as a guest are, something about his first episode just makes me go back and listen to it again and again. It's like a warm blanket for your soul.