Because I go through these stages:
1. Denial - "This question can't really be on this exam."
2. Anger - "What the Hell?! Why would this stupid professor think this is a well-constructed question? What an idiot."
3. Bargaining - "Maybe if I just write something, I will get credit."
4. Depression - "I am going to fail. This sucks. I am not going to graduate. My life is over."
5. Acceptance - ...
...I'm not there yet.