The Lie: You only use 10 percent of your brain. The Truth: You, beloved and brilliant mental_floss reader, use all of your brain. And so does everyone else. PET and MRI scans of the brain show that while you don't use all of your brain all the time, you use all of it some of the time. Frankly, we're offended on your behalf that anyone would ever say that your well-flossed, knowledge trap of a brain was only functioning at 10 percent capacity! Maybe those idiots think Van Gogh mailed his ear to a hooker, but not you! Again, even those idiots use all their brains as well, but we're on a roll here. It's totally bull! Incidentally, if you've ever wondered why we say "bull" rather than "cow" or "hog" or "three-toed possum" ...