Pooh sneezing and causing Rabbit's decorations to fly onto him.
Rabbit: Why did I ever invite that bear to lunch? Why, oh why, oh Why?"
And before that, Rabbit trying to make Pooh's bottom like a moose trophy, but Pooh giggles as Rabbit draws the mouth, making it all crooked.
Rabbit: Oh Pooh, you messed up my moose!
(cut to Pooh on the other side wearing a similar expression as the "moose")
Reportedly, Rabbit decorating Pooh's bottom was Walt's favorite scene.
When Rabbit overhears Gopher offering honey to Pooh, he yells, "Honey?! OH NO!" He then begins to run outside, only to trip over a chair with a rather priceless expression.
And shortly after stopping Pooh from eating honey and telling him that he'll taste it for him, Rabbit leaves and then comes back to hammer a sign that says, "Don't Feed The Bear" with his own fist, saying, "DON'T! FEED! THE! BEAR!"
At the beginning of the scene, Pooh is sleeping like a baby, while on the other side, Rabbit is sitting there completely stressed with eyes wide open.
"Christopher Robin, I have come to a very important decision. These are the wrong sorts of bees!"
Pooh accidentally ripping his backside during "Up, Down, Touch the Ground".
Pooh: Oh, stuff and fluff.
Christoper Robin is asking why Pooh rolled around in the mud. Pooh says in a completely matter-of-fact way "I'm a little black rain cloud, of course." It's the way that Pooh says it that really helps to sell the punchline.
Rabbit and the gang launching Pooh clean into the air when they finally force him out of the rabbit hole.
Gopher: Ssssufferin' sssassafrassss! He's sssssailin' clean out of the book! QUICK! TURN THE PAGE!(The narrator turns the page, causing Pooh to SLAM into the honey tree, sending the bees fleeing in a panic)
Eeyore: Stuck again.
Piglet trips and lands on top of the balloon he wanted to give Eeyore for his birthday. But then... POP! Everything blacks out, then we fade in to Piglet on the ground covering his eyes and besides what remains of the balloon.
"What's a Pooh?" "You're sitting on one."
Winnie the Pooh and the Blustery Day
Pooh and Piglet are blown onto Owl's window.
Owl: Well, I say now. Someone has pasted Piglet on my window.
The rest of the scene involves Pooh and Piglet being thrown across Owl's room, while Owl is oblivious to the severity of the storm outside and keeps rambling on about his family. Hilarity Ensues.
If you pay attention to that scene, the tree falls down exactly in the direction Pooh was sitting in Owl's dining room. So, as antique and fragile as the tree was already, it might have been Pooh's fault actually, making that scene's last lines funnier.
Piglet attempts to knock someone's door, at which point Pooh arrives and offers to knock for him:
Pooh: Well. Whoever lives here certainly takes a long time answering his door.
Piglet: B-b-b-b-but Pooh, isn't this your house?
Piglet comes to Eeyore revealing he brought him a present. Eeyore faints.
Tigger's persistent denial that he bounced Eeyore, complete with a very hammy recreation of him allegedly "coughing him" during the ordeal. Especially since despite Tigger's defensiveness, only Rabbit seems to particularly persecute Tigger over it. At one point Roo even happily interjects if Tigger could bounce him next.