Pharynx is a common passage for food and air. This is a place which has openings for both food pipe and windpipe. A cartilaginous flap called epiglottis prevents the entry of food into the wind pipe by covering the opening of windpipe during swallowing. When we eat the food in hurry the epiglottis gets confused between the windpipe and the food pipe and the food goes into the wind pipe thus causing violent coughing. So we must never eat our food in hurry.