There are some really funny superstitions here in Chile, one of them is called the crooked mouth. When we knock doors, a lot of people answer the door covering their mouth. The reason is because they believe that if a gust of wind touches them, it will leave their mouth crooked. It has to do with people drinking yerba mate, which is a popular drink in all of South America. I've heard various versions of the myth, but my favorite is that if you are drinking mate and you have the window open, you can't open the door because the airflow will leave your mouth crooked. Everyone has some uncle or cousin that has "the crooked mouth"
Attached is a small comic that explains that fresh air is dangerous because one cousin went outside after drinking mate and they got the boca chueca.