A lecturer tells some students to learn the phone-book by heart. The mathematicians are baffled: `By heart? You kidding?' The physics-students ask: `Why?' The engineers sigh: `Do we have to?' The chemistry-students ask: `Till next Monday?' The accounting-students (scribbling): `Till tomorrow?' The law-students answer: `We already have.' The medical-students ask: `Should we start on the Yellow Pages?'