It can be anything no matter how unsubtle or bizarre. Students are not going to scan the output to check if its correct because they 1) cannot evaluate correctness and 2) are lazy in checking as evidenced by them pasting the prompt without checking it in the first place.

Skip the instructions part (yes, it's me again, pointing that the instructions/data part of this is a silly red herring people get hung up on).

It's enough you start using shibboleth terms in key areas. Do not remark on them, just use them. There are good chances the LLM will naturally pick up and start using them too, while that document sits in context.

If anything, embedding an explicit instruction to repeat shibboleths would backfire, because AI systems nowadays run classifiers against prompt injection attacks.

Last one i read about had exactly extra instructions in white on white in the task definition document.