'Guà kē' is informal, campus slang used primarily by students to mean 'to fail a course' — especially in university or college settings. Literally, 挂 (guà) means 'to hang' and often carries the connotation of 'stalling' or 'getting stuck', while 科 (kē) refers to an academic subject or course. Together, they vividly evoke the image of a student 'hanging' — unable to move forward — because they didn’t pass a required class. It’s not used for minor setbacks like low scores, but specifically for failing an exam or course and needing to retake it.

This term is highly colloquial and rarely appears in formal documents, official transcripts, or teacher-student communications outside casual conversation. It’s common in student chats, social media posts, and peer advice ('Don’t pull all-nighters — you’ll still guà kē!'). While widely understood across mainland China, it’s less common in Taiwan or Hong Kong, where terms like '當掉' (dāng diào) are preferred.