Spock: Captain. I am only a Vulcan. There are limits.
"More Tribbles, More Troubles" is a Call Back to TOS's most hilarious episode, "The Trouble with Tribbles", and introduces a number of new gags:
Remember when Kirk accidentally sat on a tribble that was in the captain's chair? This time, there is a Running Gag where a large tribble chooses the same spot. Twice, Kirk has to shove it off. The third time, it's too large to deal with, and he concedes: "I think I'll stand."
The glommer, a critter that eats tribbles, meets a gigantic one and flees in terror.
Finally, at the end McCoy has begun to administer a treatment to the tribbles which keeps them from endlessly reproducing or forming giant colony balls. Kirk notices one that's up a Jeffries tube and calls attention to it, but he has barely finished speaking when the ball disintegrates into individual tribbles and buries the captain once again.