不三不四 disreputable
Explanation
形容人的品行不正派，行为不端正，不像样子。
Describes someone whose behavior is not correct, decent or proper.
Origin Story
话说梁山好汉鲁智深，为救金翠莲父女大闹野猪林，三拳打死了镇关西，犯下命案，被逼无奈削发为僧。他来到大相国寺，发现寺院后院的菜园被一群无赖霸占，这帮不三不四之徒不仅偷菜，还经常欺压百姓。鲁智深看不下去，决定为民除害。他先礼后兵，劝说那些无赖离开，但他们非但不听，反而变本加厉，甚至扬言要教训鲁智深。鲁智深忍无可忍，终于爆发了。他单枪匹马，闯入菜园，一番拳打脚踢，将这群不三不四的无赖痛打一顿，打得他们抱头鼠窜，再也不敢来菜园滋事。从此以后，菜园恢复了平静，百姓们也安居乐业，鲁智深也赢得了百姓的赞誉。
The story tells of Lu Zhishen, a monk from Liangshan Mountain. After being forced to become a monk, he found the monastery garden being occupied by a group of ruffians who regularly harassed the local farmers and stole their vegetables. Lu Zhishen, a man known for his righteousness, could not stand idly by. After several attempts to reason with these unsavory characters failed, he resorted to more direct methods. With his renowned martial arts skills, Lu Zhishen swiftly defeated the ruffians, chasing them away and restoring peace to the garden. The farmers were finally able to work in peace, and Lu Zhishen earned the respect of the community.
Usage
多用于形容人的品行不正派，行为不端正，不像样子。
Mostly used to describe someone whose behavior is incorrect, indecent, and improper.
Examples
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他行为不三不四，令人讨厌。
ta xingwei busanb usi,lingren taoyan.
His behavior is not decent.
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这个人说话不三不四，让人难以理解。
zhege ren shuohua busanb usi,rang ren nanyi lijie
His words are nonsense and confusing