Pick an LLM. Any LLM.
Ask it what the goat river crossing puzzle is. With luck, it will tell you about the puzzle involving a boatman, a goat, some vegetable, and some predator. If it doesn’t, it’s disqualified.
Now ask it to do the same puzzle but with two goats and a cabbage (or whatever vegetable it has chosen).
It will start with the goat. Whereupon the other goat eats the cabbage left with it on the shore.
Hopefully this exercise teaches you something important about LLMs.