Oil pulling

Oil pulling is a very, um, unusual folk remedy for just about everything. It involves swishing some oil (vegetable oil, not gasoline) around in your mouth for 10-15 minutes to detoxify your body. While not usually dangerous, it has not been proven to come close to doing everything it is said to do. (Also, oil pulling for long periods (10-20 minutes) may lead to accidental inhalation of some of the oil; it can lead to lipoid pneumonia. )

However, a study done in 2008 (a single study of 20 participants) showed that it does produce a statistically significant decrease in the amount of S. mutans bacteria, a major cause of tooth decay, in the mouth. It doesn't have as much of an effect as mouthwash does, though. It is effective against Mexican food, so there's that.

If you want to wash your mouth out to get rid of dangerous bacteria, use some mouthwash. It tastes much better. Swilling a shot of vodka around your mouth and then swallowing also works and is much more rock'n'roll. Jokes aside, ethanol dehydrates mucosa lining human mouth, therefore mouthwash have much lower alcohol concentration. In the long term strong liquors are detrimental for oral hygiene.