A yawn is a reflex of simultaneous inhalation of air and stretching of the eardrums, followed by exhalation of breath. Pandiculation is the act of yawning and stretching simultaneously. Yawning is associated with tiredness, stress, overwork, lack of stimulation, and boredom.
Yawning can also be a powerful non-verbal message with several possible meanings, depending on the circumstances.In humans, yawning has an infectious quality (i.e., seeing a person yawning, talking to someone on the phone who is yawning, or just thinking of yawning can trigger yawning) which is a typical example of positive feedback.
So yes, yawning is a natural process of life..
but what's wrong with while yawning that its better to close your mouth..
so disgusting attitude..
its better not to talk at all..