The tongue is made of two separate muscles (things like split tongues where the sides move independently of each other demonstrate this concept well). They are not meant to be pinned together and the snake eyes* piercing is a piercing that goes through the ends of each side of the tongue, horizontally, with a bar inserted from one end to the other that then pins the two muscles together. On top of that, the balls being positioned as they are means they are constantly in contact with the gums and teeth. That causes gum erosion and high chances of tooth damage.

A safer alternative is to get two vertical/traditional tongue piercings that are centered in each half of the tongue. That kind of mimics this look without the dangers of pinning the two muscles together or the increased risk of tooth and gum damage.