Kyon chalti hai pawan, Because of evaporation. Kyon jhoome hai gagan, Because of earth's revolution. Kyon machalta hai mann, Because of excessive respiration. Na tum jaano na hum. But I just gave all the reasons! Kyon aati hai bahaar, Because of a change in season, Kyon lutata hai karaar, Because of mental tension. Kyon hota hai pyaar, Because of opposites attraction. Na tum jaano na hum. Like I said, these are all science phenomenon! Kyon gum hai har disha, Because you have a poor sense of direction. Kyon hota hai nasha, Because of drug addiction. Kyon aata hai maz! aa, But science gives us all the information. Na tum jaano na hum. I did my best to explain!