Other forms: pains in the neck
A pain in the neck is any kind of annoyance or source of grief. A dead car battery can be a pain in the neck, and so can your nosy neighbor.
Have you ever had a literal pain in your neck? If so, you know how bothersome it can be, ruining your sleep and making the whole day unpleasant. When a person or problem is called a pain in the neck, it's because they're similarly bothersome. A lazy employee is a pain in the neck for the boss. A noisy student is a pain in the neck for a teacher. Difficult homework is a pain in the neck for students.