Milt Kahl sure had some fun animating dialogue scenes with Sir Kay from the Sword in the Stone.
In this scene from an early sequence Kay turns toward Wart who is observing Kay's hunting "skills" from a tree branch above.
Milt drew facial expressions and mouth configurations that let you know right away, this guy is not very bright. The puckered lips for QUIET and WART, then the wide open mouth for QUIET, and later for WART. There is comedy in the way the mouth moves during the dialogue.
When I was animating Jafar way back, I tried to aim for humor in some of his dialogue scenes.
Weird mouth shapes that would hopefully express character while still being in sync with the words spoken.
The thing with Milt is that the flat graphic character design still turns absolutely three-dimensionally in space. He could draw any mouth configuration from any angle.
Come to think of it, I would have added some teeth to the last mouth shape in order to pronounce the T in Wart. But what do I know?
Here's more on Kay: