不败少年不败菇凉
[bù bài shăo nián bù bài gū liáng]
'不败少年' refers to an unbeatable young man while '不败菇凉' is a play on words, meaning an unbeatable girl but with the word for mushroom ('蘑菇', mogu) replaced in it. This nickname shows a couple or pair of friends both wishing for invincibility.