Dudespeak is the common tongue for bandity folks on the Sphere. It's the most used language, and the unofficial one for business, and the even more unofficial one for love, with some 212 other sub-languages claiming they deserve the spot.
It's uncontested as the most widely understood. Tribes and gangs and crazies and bored fantasizing 8th graders make up or speak other languages and talk at each other with them, but most all will know some dudespeak with different degrees of fluency.