你是美男我是猪你是美女我是狼
[nĭ shì mĕi nán wŏ shì zhū nĭ shì mĕi nǚ wŏ shì láng]
If you're a handsome man then I'm a pig, if you're a beautiful woman then I'm a wolf. This implies admiration towards someone's beauty while humorously downplaying one's own appearance or qualities.