A new benchmark, CIBuzzBench, is introduced for evaluating the ability of large language models (LLMs) to understand Chinese internet buzzwords across languages. The benchmark includes 3,001 annotated buzzwords with English explanations and evaluates LLMs' performance in cross-lingual understanding, meaning explanation, and harmfulness detection. The results show that LLMs struggle with fine-grained non-literal interpretation and equivalent matching, highlighting challenges for multilingual LLMs and safety-oriented evaluation.