The Vietnamese phrase "cắm cổ" is an informal expression that conveys the idea of being completely focused on a task or activity, often to the exclusion of everything else around you. It can also imply a sense of urgency or intensity in the action being performed.
Cắm cổ chép bài: This means "to be completely wrapped up in copying one's lesson." For instance, if a student is so focused on copying notes from a lecture that they don't notice anything else around them, you can say, "Cô ấy cắm cổ chép bài suốt giờ học."
Sợ quá, cắm cổ chạy một mạch: This translates to "frightened out of his wits, he ran off without turning his head once." It describes someone who, in fear, runs away quickly and without looking back at all.