Also known as: くしゃみ
A single, involuntary reflex where the lungs fully inhale and sharply exhale through the mouth and nose to eject parasites and dust from the breathing system. Can be caused by disease and irritating dust. Differs from a cough, which is only through the mouth and is used to clear the airway, a sneeze is more like scratching an itch inside the nose.
Japanese folklore says that you sneeze when someone is talking about you behind your back.