[Tidus is confused at first, but he soon smiles and holds up a ball.]

It's only the greatest sport in the world! It's played underwater with teams of six players, five in the field and a goalie to guard your goal. You compete against the other team for the ball, then try to shoot as many goals as possible while stopping the other team from scoring.

Does that make sense? We could do a mock-game on the sand if you want.