Meaning:
“水” means “water,” and “课” means “courses.” Either alluding to “water-injected” or “smuggled in by waterways,” the Chinese word “水” here means “unworthy, of poor quality.” Often heard from college students, this term refers to those undemanding courses that fail to interest and stimulate students. While it’s easy to pass the exams and get academic credits through them, students find it hard to actually learn anything useful.
Example:
A: 下学期除了专业课，你打算选哪些选修课？
Xià xuéqī chúle zhuānyèkè，nǐ dǎsuàn xuǎn nǎxiē xuǎnxiū kè？
Which elective courses do you plan to attend apart from the compulsory ones required by our major?
B: 这门电影欣赏我很感兴趣。
Zhèmén diànyǐng xīnshǎng wǒ hěn gǎnxìngqù。
I’m interested in “Film Appreciation.”
A: 这个貌似是水课，学不到什么。
Zhège màosì shì ，xuébudào shénme。
This one looks like a fake, and you can’t expect to learn anything. But it might be easy to pass the exams.