二逼青年欢乐多四逼青年仇人多
[èr bī qīng nián huān lè duō sì bī qīng nián chóu rén duō]
This humorous phrase, 'Happy-go-lucky Foolish Youth, Quarrelsome Older Fool,' contrasts two stages of immature behavior in a somewhat self-deprecating manner. The former part describes carefree immaturity while the latter refers to someone more trouble-prone as they age.