I think this is easy, just make Xp sentences of the kind = "I define `randomchars()` to be this `term-in-Xc()`" and swamp the dataset with Xc.
Everything here actually just follows formally from what NNs are: they're just empirical function approximations.
It will always be the case that they just model the probabilistic structure of the dataset and not the data generating process.
Since, in language, there are discrete constraints which make P(...) = 1 or P(...) = 0 --- you can trivially produce datasets showing that it learns P(...) = mistake-you-created-deliberately and not either 0,1.
As above, the LLM switches from 95% confidence "chocolate" to 95% confidence "popcorn" with a trivial non-semantic permutation of the prompt.
The obscene issue in all this is that we know this already -- empirical function approximation of historical datasets just produces associative probabilistic models of those datasets.