can hair grow in your mouth
Black hairy tongue is caused by bacteria or fungi in the mouth, which make the tongue appear black and hairy. It's easily remedied by good old-fashioned oral hygiene. A black hairy tongue is caused by too much bacteria or yeast growth in the mouth. The bacteria build up on tiny rounded projections called papillae. These lie along the surface of the tongue. Instead of shedding as they normally do, the papillae start to grow and lengthen, creating hair-like projections.