名草有主拒绝骚扰名花有主拒绝追求
[míng căo yŏu zhŭ jù jué sāo răo míng huā yŏu zhŭ jù jué zhuī qiú]
This username is often used humorously by someone who is already in a relationship to discourage unwanted advances, indicating they're not available for dating. Literally means “the owned flower and grass refuses any pursuit or harassment”, symbolizing that they are taken.