Sometimes a rikishi may wear his mawashi in such a way as to give him some advantage over his opponent. He may wear it loosely to make it more difficult to be thrown or he may wrap it tightly and splash a little water on it to help prevent his opponent from getting a good grip on it.
Many rikishi are superstitious and they will change the color of their mawashi to change their luck. Sometimes a poor performance will cause them to change colors for the next tournament in an attempt to change their luck for the better.