OpenAI Codex system prompt includes explicit directive to "never talk about goblins"

OpenAI’s open-source Codex CLI revealed base instructions for GPT-5.5 that tell the model not to mention goblins, gremlins, raccoons, trolls, ogres, pigeons, or similar creatures unless clearly relevant.

The unusual guardrail has drawn attention online and suggests OpenAI may be trying to curb odd model behavior users have noticed.

OpenAI says the instruction is not a marketing stunt, even as executives have joked about the goblin rule publicly.