Doctor's Orders from start to finish, for Leonard McCoy; indeed, from her Trek work, one may confidently deduce that the good Doctor is Duane's all-time favorite.
That's nothing. Remember the bit in Spock's World with McCoy's epic verbal smackdown of THE ENTIRE PLANET VULCAN?
Oh, and let's not forget afterward, where McCoy informs Spock that his epic, epic speech was "every argument I've ever had with you, rolled into one." To which Spock coolly replies, "Then I would say you won."
The entire crew of the Enterprise gets one in The Wounded Sky, when they travel to the proto-universe next door and, well... to say anything more would be spoiling it.
Naraht get one in The Romulan Way when he tunnels up through the floor of the Romulan Senate and helps McCoy escape under the noses of about a bazillion guards.