Why do i have a small black pimpel on my tongue?

Melanin spot : If it's always been there, it's probably a melanin spot. Just normal pigmentation and benign. If you are otherwise healthy, the you shouldn't worry about it unless it changes.

Get seen soon: Could be from a burn. Could be normal anatomy, like a freckle. May be a bruise from an injury. Worse case scenario -- cancer --seek a diagnosis from a dentist or physician.