Like an airport

Often times, students are asked to answer a question that they do not understand. Usually they sit quietly in embarrassment or say "I don't know." But some students, in their never ending quest to attain participation points, create unusual metaphors that are often unrelated to the material being covered in class. Thus, "...like an airport..." was created. Like an airport can be used in any situation: "What caused the current economic crisis?" "Well, the economic crisis is like an airport, planes (or money) take off from the runway (or banks) and never come back. That causes banks to fail, thus creating an economic crisis." As you see, the phrase "like an airport" can get a student out of any pickle.