Some fans of today's modern franchise shows, such as Star Trek: Strange New Worlds, may not realize how important Star Trek: The Original Series is to the overall canon. It's where all the worldbuilding began, where Starfleet and the Federation got their start, and where our beloved characters established their place on the USS Enterprise, not to mention each other's lives.
This includes Mr. Spock and Dr. Leonard McCoy, whose epic bantering has, by this time, become a staple of the series. They had plenty to bicker and banter about in season 2 but certainly weren't finished. So, let's check out TOS season 3 for some of their best exchanges yet.
1. "Spock's Brain"
This is the episode that launched the third season, and it's widely considered the worst of the series. I must disagree, and if you've sat through "And the Children Shall Lead," you will understand. While the premise of Spock's brain going missing and FrankenSpock are a bit silly, it's also amusing to watch Spock infodump about how "a male-female schism took place," to quote him at the end of the episode.
Dr. McCoy in that moment says, "I knew it was wrong, I shouldn't have done it. I should have never reconnected his mouth." This results in Spock arching his head back and his eyebrow up, which is something Bones knows so well. It also seems to say, "Game on," while letting Bones know he'd done well. Leonard Nimoy's body language especially sells the scene.