Mental Floss can be anything you use as a form of mental hygine. Think of it as the same way as dental floss: Use it to get rid of the gunk in your mind.
Mental Floss comes in many forms, many we don't even recognize. Many times, we don't even recognize when we're using it. It can be as deliberate as Meditation, a spirit quest, the use of hallucinogenic drugs, or thearpy among other things. Mental Floss can also be as simple and incidental as talking to others about our frustrations to others, crying, prayer, physical activity.
Trying to overcome prejudice, preconceptions, experiences, circumstances, bad habits (physical and mental), and other barriers can also serve as a sort of mental floss.
Just as with dental floss, be sure not to floss your mind so hard that it damages your mind, your brain, or the rest of your body.
Mental Floss prevents Moral Decay.