[Early in the party]
Sounds kind of dull... [Honestly!]
It's a fun sport. You have two teams divided by a high net, and it's played with a ball that both teams are trying to get to land on the other side's playing area. The job is, basically, to keep that from happening, or to score points. [With a few hand gestures.] You have to have fast reflexes, be quick on your feet, and have good aim!
...for added difficulty, people play it on the beach in the sand.