A woman goes to a doctor's office

A woman goes to the doctor to ask about her husband's temper.
The Doctor asks: "What seems to be the problem?
The woman says: "Doctor, I don't know what to do. Every day my husband seems to lose his temper for no reason."
The Doctor says: "I have a cure for that. When it seems that your husband is getting angry, just take a glass of water and start swishing it in your mouth. Just swish and swish but don't swallow it until he either leaves the room or calms down.”
Two weeks later the woman comes back to the doctor looking fresh and reborn.
The woman says: "Doctor that was a brilliant idea! Every time my husband started losing it, I swished with water. I swished and swished, and he calmed right down! How does a glass of water do that?"
The Doctor says: "The water itself does nothing. It's keeping your mouth shut that does the trick".