The Shower is a well known juggling trick, in which one hand throws the objects across in the usual way, while the other catches them, and gives them back to the throwing hand with a short, horizontal pass.
A three club shower is usually done using double spins, although some people find either singles or triples to be easier, so try all 3 for yourself. When transferring the clubs from the passing hand to the throwing one, it will be easier at first to actually hand the club across, rather than throwing it.
Some people find that when showering clubs, they tend to turn in a circle, usually in the direction of the hand that is throwing. There are two ways to combat this turning. Either angle the clubs inwards before throwing:
or throw with outside flats. Using outside flats may seem harder at first but in my opinion it looks a lot better, especially to an audience in front of you. Alternatively, just allow yourself to turn as you shower, as long as the pattern keeps going there is no need to fight it.
Club multiplexes fit quite naturally into a shower. Simply keep hold of a club in your throwing hand instead of throwing it, place the next club that arrives on top of it, and then throw the pair together. Refer to the section on multiplexing for more details about how to stack and release the clubs. Multiplex throws in a shower look much better on flats, either inside or outside. You can either throw both clubs to the same height, and catch them simultaneously in different hands, or you can throw them to different heights, and catch them both separately in the passing hand, as if they were consecutive individual throws.