A new case study was recently published in the New England Journal of Medicine about a 55-year-old woman in Missouri, who had little black hairs growing on her tongue.
She went to the hospital after feeling nauseated, having a permanent bad taste in her mouth, and hair on her tongue.
Fortunately for her, the doctors knew why it happened. She recently had surgery after a serious leg injury, and developed an infection. Doctors put her on antibiotics.
WARNING – it’s gross!

courtesy nejm.org