Not very high brow, but this happens a lot in good children’s movies, with adults laughing at moments when the kids don’t understand why. My favourite is in Shrek when he’s walking across an onion field trying to contemplate how troll are like onions, but gets constantly interrupted by Donkey.

In Peer Gynt, the protagonist picks up an onion after having considered marrying into a family of trolls. He starts out by comparing himself to the onion, exactly like Shrek, in that he has multiple layers. However, as he’s not being interrupted by Donkey, Gynt keeps removing layers until he realizes there’s no core - the onion, like himself, is just a bunch of thin layers with no real central identity or reason to exist.

Shrek never gets to make this realisation, because Donkey keeps insisting nobody likes onions: he would be better off comparing himself to a parfait, as they also have multiple layers.

What’s a bit of a turning point of self-insight in the beginning of Peer Gynt is ruined by Donkey in Shrek, rendering it instead a commentary on how everybody loves perfait.