姐的大姨妈比你红
[jiĕ de dà yí mā bĭ nĭ hóng]
Sister's '大姨妈'(dàyímā)is slang for menstruation. So '姐的大姨妈比你红' roughly translates to 'My period is more red than yours,' implying an unimportant comparison between individuals, usually with sarcastic overtones about insignificance.