Some kid did one of those during one of my exams last semester. It was in a room of about 500 and he sat front row center. He started crying about 30 minutes into it and ripped up the exam, threw it in the air, and ran out screaming. The TA's ran out after him but he got away. It was kindof funny because everyone thought it was for real. But it was only later i found out he wasnt even in the class and he got dared to by some friends. Needless to say, i did good on that exam.