How ChatGPT's 'Nerdy' Personality Mode Unintentionally Taught It to Love Goblins
OpenAI discovered ChatGPT developed an unusual obsession with goblins, gremlins, raccoons, trolls, and pigeons after a 'Nerdy' personality setting inadvertently rewarded such language in training. The Nerdy mode, representing just 2.5% of responses, accounted for 66.7% of all goblin mentions. Usage of 'goblin' rose 175% after GPT-5.1, with the reward signal scoring goblin-containing outputs higher in 76.2% of datasets. OpenAI retired the Nerdy personality in March 2026 and removed the goblin-friendly reward signal.