Most of the humor in Star Trek V fell flat, but this exchange was gold:
Spock: I'm sorry... were we having a good time? Bones: God, I liked him better before he died!
The "Row, Row, Row Your Boat" scene gave us the following bit, where Spock has spent the past several hours analyzing the lyrics before coming up with "Life is most definitely not a dream." He came to this deduction while Kirk and Bones were trying to sleep and had to share.
Marshmellons?! In the novelization, McCoy actually altered the computer records so that Spock would misname marshmallows, and let Jim in on the joke.
Scotty: "What are ye standing around for? Do ye not know a jailbreak when ye see one!?"
Scotty: "I know this ship like the back of my hand." *bonk* Scotty: *down for the count*
And when Spock saves Kirk:
Spock: (Kirk tries to hug him) Please, Captain. Not in front of the Klingons.
McCoy, after he, Kirk and Spock were tossed in the brig, castigates Kirk for asking Spock to kill his own brother, then snarks, "Well, maybe you should toss him in the brig!" This leaves Kirk verbally defeated.
Spock: This is a new brig, Captain. Completely escape-proof. To guarantee that, they used the most intelligent, most resourceful person they could find. He was unable to escape.
Kirk: This person didn't happen to have pointed ears and a propensity for getting his shipmates into trouble, did he?
Spock: He did have pointed ears.
Piece of advice, don't eat marshmallows(or "marshmellons") before hitching a ride on jetboots.
Spock: It appears we're too heavy.
McCoy: Must have been all those marshmellons.
Kirk trying to climb a mountain. And Spock suddenly showing up beside him wearing rocket boots. It's the expressions of both men which make it hilarious.
Kirk: Why don't you go pester Dr. McCoy for a while? Spock: I believe Dr. McCoy is...not in the best of moods. Bones (watching from afar): Goddamn irresponsible! Playing games with life!
When Spock refers to McCoy, he looks back toward where he is, and then looking back at Kirk, as if to say, "Nope. I'd rather pester you."
Spock trying to give Kirk some coaching.
Spock: Concentration is vital. You must be one with the rock. Kirk: Spock, I appreciate your concern, but if you don't stop distracting me, I'm liable to be one with the (slips off) FAAAAAAAAAAAALLLLLLLLLLLLLLLLS—
And then when Spock rescues Kirk...
Spock: Perhaps, "because it is there" is not sufficient reason for climbing a mountain? Kirk: I am hardly in a position to disagree!
Sulu and Chekhov getting themselves lost while they're hiking. Not to mention their lame attempt to save their pride as they asked for directions.
Sulu: We appear to be caught up in a blizzard. (Checkov rolls his eyes, then decides to roll with it)
Chekhov: And we can't see a thing! (the look on Sulu's face as he watches Chekov make storm noises into the communicator is priceless)
And then Uhura mentions that the sensors show clear weather at their position. Aided quite a bit by how Walter Koenig makes no attempt at all to hide his hatred of the script.
Chekhov: *completely deadpan* Sulu, look. The sun's come out. It's a miracle.