Snakes don't sting or use their forked tongues as weapons. The tongues are perfectly harmless.

A snake sticks out its tongue to collect data for its Jacobson's Organ, an organ strategically located in front of the roof of the snake's mouth that functions as a chemical receptor. Each and every time the snake flicks out its forked tongue, it snares chemical particles in the air, which latch onto, or dissolve in, the moisture of the snake's tongue. Once the snake reels in its tongue, it inserts the tips of the forked tongue into the two awaiting openings of the Jacobson's organ where the particles, especially those of animal body odors, are identified, analyzed, and acted upon.

For the male snake, the tongue is both a sensory organ, and a sensual organ. The tongue plays a vital role in snake courtship and reproduction, as the male snake's jerking body motions and rapidly flicking tongue either charm the female snake, or render her unresponsive. In either instance, by sticking out their tongues, snakes ensure the survival of the species.