There is a certain something in P. G. Wodehouse's precise articulation of lunacy that brings the reader moments of great jollity.
Right Ho, Jeeves
The telegram war between Bertie and his Aunt Dahlia. Read it here, in all its glory.
Aunt Dahlia: Deeply regret Brinkley Court hundred miles from London, as unable hit you with a brick. Love, Travers.
Bertie and Jeeves's eyebrow competition.
I consulted Jeeves once more in the language of the eyebrow. He raised one of his. I raised one of mine. He raised his other. I raised my other. Then we both raised both. Finally, there seeming no other policy to pursue, I flung wide the gates and Tuppy came shooting in. "Now what?" I said, as nonchalantly as I could manage. "Why was the door locked?" demanded Tuppy. I was in pretty good eyebrow-raising form by now, so I gave him a touch of it.
"And if I portrayed the scene with anything like adequate skill, the picture you will have retained of this Fink-Nottle will have been that of a nervous wreck, sagging at the knees, green about the gills, and picking feverishly at the lapels of his coat in an ecstasy of craven fear."
The entirety of Joy in the Morning (US: Jeeves in the Morning), but especially the moment at which Bertie finds himself 'a gazelle short.'
Bertie: You don't mind me referring to you as a gazelle, do you, Jeeves?
Jeeves: Not at all, sir.
"If that doesn't leave me without a stain on my character, well, then I don't know what it does leave me without a stain on."
The climactic rugby match in The Ordeal of Young Tuppy:
He was so crusted with alluvial deposits that one realized how little a mere bath would ever be able to effect. To fit him to take his place once more in polite society, he would certainly have to be sent to the cleaner's. Indeed, it was a moot point whether it wouldn't be simpler just to throw him away.
In "Jeeves and the Yule-Tide Spirit", Jeeves advises Bertie against pursuing Bobbie Wickham, calling her "volatile and frivolous." Later in the story Bertie tells Jeeves that he's about to eat his words: Bobbie just gave him an excellent plan to prank Tuppy Glossop by puncturing his hot water bottle, "and this is the girl you were calling volatile and frivolous."
Jeeves reads over Bertie's article on "What the Well-Dressed Man Is Wearing" for Milady's Boudoir:
I watched him narrowly as he read on, and, as I was expecting, what you might call the love-light suddenly died out of his eyes. I braced myself for an unpleasant scene. "Come to the bit about soft silk shirts for evening wear?" I asked carelessly. "Yes, sir," said Jeeves in a low, cold voice, as if he'd been bitten in the leg by a personal friend.
Bertie reflecting on the refining effect of suffering in The Aunt and the Sluggard:
As I stood in my lonely bedroom at the hotel, trying to tie my white tie myself, it struck me for the first time that there must be whole squads of chappies in the world who had to get along without a man to look after them. I'd always thought of Jeeves as a kind of natural phenomenon; but, by Jove! of course, when you come to think of it, there must be quite a lot of fellows who have to press their own clothes themselves, and haven't got anybody to bring them tea in the morning, and so on. It was rather a solemn thought, don't you know. I mean to say, ever since then I've been able to appreciate the frightful privations the poor have to stick.
A memorable scene in The Mating Season occurs when Police Constable Dobbs, in hot pursuit of Gussie Fink-Nottle, chases him up a tree.
And what he [Gussie] expected to get out of this maneuver, only his diseased mind knew. Constable Dobbs may not have been one of Dorsetshire's finest thinkers, but he was smart enough to stand under a tree. And this he proceeded to do. Apparent in the lines of his broad back was the determination to fight it out on these lines if it took all summer[...] I closed my eyes to shut out the painful scene. When I re-opened them[...] I beheld the officer flat on his back in the middle of the road, while Jeeves was replacing something in his pocket which instinct told me was small, serviceable, and made of India-rubber.
"I coshed the officer, sir," said Jeeves respectfully. "It seemed to me the best course to pursue."
The TV series
The end of the episode "The Hunger Strike," with Bertie's perfectly innocent "Me? W-what have I done?" a few moments after he'd accidentally shot a chandelier off the ceiling with a hunting rifle.
Whenever Jeeves shows disapproval on any of Bertie's (or Bertie's friends) crazy fashion statements. From a white Mess jacket with brass buttons to a tie with horseshoes on it to Bertie's mustache. Made even funnier with Stephen Fry's wonderful facial expressions.
Particularly the moment where Rocky reveals that he "dresses" by throwing on a sweater over his pajamas: