If you like to stick your tongue out at yourself in the mirror while brushing your teeth—or perhaps for no reason at all—you may have noticed your tongue is not totally smooth. According to the American Academy of Oral Medicine, a cracked tongue is known as a fissured tongue. Brushing the tongue with a toothbrush or tongue cleaner—a stiffer brush that can easily remove particles—is recommended. Fissured tongue is also associated with another peculiar oral mystery—geographic tongue. Like fissured tongue, it’s essentially harmless, though the affected areas may occasionally feel irritated.