A tongue orbital is two normal tongue piercings with a single ring placed through them. It is important to note that a tongue orbital should never be attempted in a fresh piercing. Wait at least a month, or tongue swelling could easily cause the ring to become fully buried and embedded inside the tongue. This can even happen with healed piercings, so keep an eye on it. Once the swelling gets past a certain point it can become very difficult to extract the ring.
Care must also be taken with the placement to ensure the tongue's mobility is not affected. If it is, both eating and talking will be compromised to some extent.