One of the things that I think surprises some people is just how funny Nimoy could be and I think that helped him add depth to the character of Spock, he didn't fall into the trap so many characters of his type do of not being able to understand jokes. He may not have laughed but he knew when someone was making one and he could fire back at McCoy and that just gave the character a whole new level that went beyond him just being the stoic alien who didn't understand humans but was super smart.

Nimoy did enjoy comedy and could be a really funny guy. I remember in one of his books he said that he thought a lot of the best McCoy/Spock scene could be rewritten for Abet and Costello. He then proceeded to rewrite Who's on First for Spock and McCoy. I laughed really hard when I read that as a kid.