If you told them to write a Lewis Carroll poem about a nonsense word, it wouldn't have any problem. Not because it "recognizes" the word as being like a nonsense word in a Lewis Carroll poem, but because those poems are filled with other un-tokenizable words that could be replaced with anything.
I'm starting to come to the conclusion that LLMs are Mad-Libs at scale. Which are actually very useful. If there are paragraphs where I can swap out the words for other words, and generate a plausible idea, I can try it out in the real world and it might really work.