It could be perhaps that his shoes were too tight.
6 seconds sound clip from the How the Grinch Stole Christmas! (1966) movie soundboard.
You can hear this line at 00:02:33 in the Blu-ray version of the movie.
Quote context
[...]
- Christmas comes tomorrow. Trim you, trim me.
- Trim up the tree with fuzzle fuzz and bliffer bloofs, and wuzzle wuzz.
- Trim up your uncle and your aunt with yards of whofont flant.
- It could be perhaps that his shoes were too tight.
- It could be his head wasn't screwed on just right.
- But I think that the most likely reason of all may have been that his heart was two sizes too small.
- But whatever the reason, his heart or his shoes, he stood there on Christmas Eve hating the Whos.
[...]