My bf wants to get his tongue pierced but uses smokeless tobacco?

Two bad things: Use of tobacco in any form is bad for one's health. Piercing the tongue can lead to infection and chewing tobacco at the same time can only make it worse.

Problem: With or without smokless tobacco - it is dangerous. Tongue barbells can chip or fracture front teeth. Gums can be damaged by the rubbing of barbells requiring periodontal surgery. An unscrewed barbell may be aspirated into the lungs. Infections can be quite severe & eventually lead to disfigurement. There can be significant blood loss & permanent neuralgia (pain).