Form of juggling involving multiple people throwing clubs back and forth between them. It's very social.
The most common pattern is probably "quick-start, every-others". "Quick-start" means you start with a right-hand pass immediately (as opposed to starting with one or more self throws); "every-others" means that you pass every other right-hand throw. Also very common is a simple "feed", where the feeder passes every right-hand throw, but alternating between two (or more) feedees. Thus, as soon as you can do every-others, you can be a feedee.
Slightly more difficult is the 3-count, where you pass every third throw, but counting both hands. So you have a right-hand pass, left-hand self, right-hand self, then left-hand pass, right-hand self, left-hand self, then right-hand pass again, and so on. And again, a feed can be done, with the feedees each doing a 3-count.