Oh gosh I like the idea of that being codified.
<textarea user-reply-warning="THINK AGAIN IF YOU'RE GOING TO EXPLAIN THIS TO ME"></textarea>
Sometimes mine would be:
<textarea user-reply-warning="I wasn't asking for feedback on this so if you give me feedback and I don't know you and it stinks I will block you with no regret whatsoever"></textarea>
Rather than a content warning, it's an interaction warning.