The very idea of seeing a criminal penguin as the antagonist.
Gromit threatens Feathers McGraw with a rolling pin. Feathers pulls out a revolver. Gromit instantly throws his arms up.
Wallace's wild race around the town in the techno-trousers, controlled by Feathers McGraw. Particularly the shot of Gromit looking at a poster in the foreground, when Wallace suddenly whizzes past in the background, trying and failing to hang onto a lamppost, yelling for Gromit, who then looks around as if to say, "Somebody call my name?"
"Dog Reads Paper". And below it: "Sheep Found Guilty".
Wallace balancing on the train. In the Techno-Trousers. And later in just his vest and underpants.
The entire train chase (on a toy train, no less) is three minutes of pure hilarity. The best part has to be Gromit laying down track rapid-fire as they go.
A Close Shave
Wallace and a bunch of sheep break Gromit out of prison by forming a tower. Then Wallace steps on a bar of soap, falls to the ground, and looks up at the sheep as they fall on top of him.
Wallace and the entire herd of sheep are chasing Preston's truck, all on one motorcycle. Wallace yells for them to "get yourselves organised down there!". A moment later, Preston does a double-take as he looks in the side-mirror and see the sheep and Wallace in a perfect jet-ski style formation on the motorbike.
Then Preston decides to try and scrape them off by going under a viaduct, only for (in a sort of inverted Impact Silhouette) the sheep to quickly rearrange themselves into a horseshoe-shaped formation so they all fit through the hole.
The porridge scene where the porridge keeps hitting Wallace until Gromit shuts it off.
Wallace goes through an epic Thunderbirds style sequence to get into his window washing gear...and then Gromit just walks through the door into the garage and rolls his eyes.
Wallace seeing his new sheep with no fleece left and deciding to name him Shaun.
"Just a bit of harmless brain alteration, that's all."
Most of the Double Entendres in Curse of the Were-Rabbit, but the box Wallace uses to cover himself reading "Warning: Contains nuts" is a standout.
The villagers' meeting gives us one of the most perfect Face Palm moments ever, after Lady Tottington suggests giving Anti-Pesto a second chance:
Victor: How on earth would those tiny-minded buffoons ever catch such a big rabbit? Lady Tottington: Mr. Wallace? *turns to him* Wallace: Um...well, uhh... *beat* With a big trap! * cue epic Face Palm from Gromit* Villager: By Jove...he's got it! * cue the other villagers all congratulating Wallace*
The plane fight with Gromit and Phillip. Specifically when it's interrupted by the plane's time running out and requiring the entire fight to cease as the combatants root around for change.
Made funnier by Phillip's brightly-colored, flower change-purse. Mostly because it is definitely not what you'd expect a dog like him to have.
First Victor's hair, and then Victor himself, being sucked into the Bun-Vac.
Another Victor moment: after Victor arrives at the vegetable competition to tell Constable Mackintosh that the Were-Rabbit isn't dead yet, Mackintosh accidentally yells it into a megaphone while standing in front of the crowd. Some cotton candy tumbleweed blows past, Mackintosh quietly says, "...Oops", and then everyone panicks. That's pretty funny, but what makes it even funnier is that in the foreground as Mackintosh says "Oops", Victor is facepalming and slowly shaking his head in exasperation. There's something about it that just looks so SILLY.
And then when Victor, trying to get the panicking crowd's attention, fires his gun in the air...which was loaded with the second of three golden bullets.
Victor: I've only got two...(Beat) I've only got one gold bullet left!
Not to mention, in between Macintosh yelling and the crowd going mad, there's a small space where everyone stands absolutely still in sheer horror. And some candyfloss is blown away.
And then Victor letting out a Big "NO!" and then throwing a tantrum and screaming, "Potty poo!" after Gromit rescues Were-Rabbit!Wallace by having the Golden Carrot Award hit his plane instead.
Wallace reading "Ay-Up!" magazine in Were-Rabbit.
Even though Wallace's first transformation is pretty scary, there's one part in there that's funny: Victor looking at Gromit and Gromit shrugging.
Also, when Victor is going to the Vicar for advice, each dramatic sentence is punctuated by some Dramatic Thunder...up until Victor closes the shutters so they can talk normally.
This line from the Vicar when he and the mob are chasing after Victor disguised as the Were-Rabbit:
"Destroy! Drive out the monstrosity!"
Another line from the Vicar after Victor gets his trousers caught on a weather vane: