Meaning:
This word literally means “cabbage,” which is not what we’re talking about here. “卷” is used in the sense of “内卷” (nèijuǎn, meaning “involved in over competition”), and “菜” implies “being unskillful at,” as in “菜鸟” (càiniǎo, referring to a “rookie”). This term coined by Chinese netizens refers to those who willingly participate in or are forced into over competing, but often fail in their attempts due to a lack of competence or experience. With a tint of mockery, it’s not a nice word to say about others.
Example:
A: 你给孩子报了几个兴趣班？
Nǐ gěi háizi bào le jǐ ge xìngqùbān？
How many extracurricular programs have you booked for your kid?
B: 完全没有。学校的作业每天都忙到晚上十点，不希望他变成苦恼的卷心菜。
Wánquán méiyǒu。Xuéxiào de zuòyè měitiān dōu mángdào wǎnshàng shídiǎn，bù xīwàng tā biànchéng kǔnǎo de juànxīncài。
None. He can’t finish his homework before 10 p.m. every day. I don’t wish to force him into fierce competition beyond his capability.