Yaaawwwnnn

Someone asked me about the anatomy of a yawn. In my research, look what I found:

The Ancient Greeks believed that yawning was not a sign of boredom, but that a person's soul was trying to escape from its body, so that it may rest with the Gods in the skies.

Some say that yawning is caused by the Devil, who sends evil spirits to enter a person's body when his or her mouth is open. Thus, covering one's mouth prevents the evil spirits from entering.

Some people cover their mouths because they are afraid their bad breath will put people off.

OK, I made up the last one. But I'm sure it's true.