'The Goblins Came Back to Haunt Us': OpenAI Explains How ChatGPT's 'Nerdy' Personality Got Out of Control

Earlier this week, OpenAI posted a document on GitHub as part of the open-sourcing of its coding agent, Codex CLI, that revealed an unusual system prompt for GPT-5.5. The model was explicitly instructed, in coding contexts, to never talk about “goblins, gremlins, raccoons, trolls, ogres, pigeons, or other animals or creatures” unless it was “absolutely and unambiguously relevant” to a user’s request. Now, OpenAI has finally explained why that oddly specific instruction, which appeared twice in the prompt, was so important in the first place. For at least a year, some ChatGPT users have noticed the LLM’s quirky habit of bringing up goblins, gremlins, trolls, and other creatures in its answers. The weird tic apparently became more common as newer models rolled out. Even OpenAI CEO Sam Altman referenced the issue in a post on X Monday morning. “Feels like codex is having a ChatGPT moment,” Altman wrote. “I meant a goblin moment, sorry.” That same day, OpenAI published a blog post explaining the strange behavior and how the company finally addressed it. According to the post, OpenAI first became aware of the model’s goblin obsession with the release of GPT-5.1 in November. The company