Someone called me a 废柴码农 after I made a silly mistake. I suppose it must be something negative but what does it actually means?
废柴码农 means something like incompetent programmer. Usually 废柴 is used as a noun, for example, many fans of Man United say Darren Fletcher is 废柴. 码农 is a self-deprecating name for programmers, and its original meaning in Chinese is coding peasant.
It's an informal, mocking expression used only on the internet. Don't take it seriously or use it in real life.
廢柴碼農 means useless coding farmer.
碼農 is a word used in Mainland China. In Mainland China, farmers (農) are lower class and not supposed to be respected. Describe a programmer as farmer is not respect to your job.
廢柴 is a borrow word from Cantonese. It is to describe a person useless.
From baidu: 废柴，起源于粤语，多为骂人的词，随着《废柴兄弟》播出，废柴被衍生为坚持梦想的有（mei）为（qian）青（de）年（ren），其中在剧中的一对废柴许之一和张晓蛟被成为“柴帝”。“废柴”是一种社会现象，表面上看着很废，其实很有才，总有被燃烧的一天。废柴是一个自嘲式的正能量词语，多用于网友的自嘲，预示具有强大潜力。
廢柴 usually used to describe someone who is a "rubbish", a weak person.
This word is very common in Hong Kong, it is not a foul language, but not polite