"A sneeze is not just your mouth and nose," A.J. says. "It's a full body reflex, so it involves the stomach, your head and your lungs. It puts a lot of pressure on your head and you close your eyes sort of as a protective measure. And by the way, you should never stifle a sneeze—if you hold your nose, the air goes out your ears and that puts pressure on your ears. So just let it go."