students laughing

1, an old president,lecture to the students. After a few hours, the principal wake up when he said: "I feel very strange, why each finished layer of meaning, have heard two-wave-style applause? Later, after careful observation, finally understand,reason is to from the applause of those who listen, wake dozing, so causing a second wave of applause.So students are my observation is true? " President just said that finish, the audience roared with laughter, also two-wave-like applause. At this time, the principal also laugh. His laught drew the third wave of applause.
2, mechanical engineering, electrical professionals and computer science students to travel by car, the car suddenly breaks down, three people get off and check. Mechanical engineering students: It seems there is some engine problem. Electrical students: also a little leakage. They all looked at computer science students: how do you see? Computer science students: a little problem, system halted,and restart!