HumorReject: Decoupling LLM Safety from Refusal Prefix via A Little Humor
Zhiwei Wu, Haichang Gao, Jiacheng Luo, Zhaoxiang Liu · Preprints.org · 2025
Large Language Models (LLMs) commonly rely on explicit refusal prefixes for safety, making them vulnerable to prefix injection attacks. We introduce HumorReject, a novel data-driven approach that fundamentally reimagines LLM safety by decoupling it from refusal prefixes through the use of humor as an indirect refusal strategy. Rather than explicitly rejecting harmful instructions, HumorReject responds with contextually appropriate humor that naturally defuses potentially dangerous requests while maintaining engaging interactions. Our approach effectively addresses the common "over-defense" issues in existing safety mechanisms, demonstrating superior robustness against various attack vectors while preserving natural and high-quality interactions on legitimate tasks. Our findings suggest that innovations at the data level are even more fundamental than the alignment algorithm itself in achieving effective LLM safety, opening new directions for developing more resilient and user-friendly AI systems. Our code and dataset are available at https://github.com/wooozihui/HumorReject