In juggling, a version of the four ball fountain where the two hands throw together instead of alternately. Most people find it harder than the normal, or 'asynchronous' pattern, but there again you're not most people, are you? 8^)
To move from the asynchronous to synchronous pattern, you need to throw one ball slightly higher than the others... i.e., if the normal pattern is "4444", then throw "444454"... the ball should land at approximately the same time as the next one in your other hand. Then, just keep throwing balls at the normal height, but at the same time from each hand.
Moving back from synchronous to asynchronous fountain is a little harder, since you'll have to throw a ball slightly higher from one hand than the other, but while throwing them at the same time. This is annoying. Very annoying. However, I don't worry about this, since I always mess up the synch fountain anyway.
One trick that synchronous throws make possible is the crossover throw. Throw each ball to the opposite hand, then catch and resume the regular pattern. Of course, the big problem here is that they could well hit each other in the air... if you're accurate enough, then try throwing one in front of the other. Otherwise, just throw and hope! The crossover looks very nice when thrown every other throw.
Another trick for the synch fountain is the four ball split; you throw two balls up at once side by side, then throw the other two side by side on the opposite site of the pattern. In other words, the balls in column 1 and 2 are in synch, and the balls in column 3 and 4 are in synch. This is very hard, since both hands are moving rapidly from one side of the pattern to the other. Only attempt if you are seriously good at four ball juggling.
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