Five Ball Shower
The Five Ball Shower is, as it
sounds, a five ball version of the Shower pattern. This means that it is
juggled higher and faster than the Four Ball Shower (and much higher and
faster than the regular Shower), and as such you should already be very
comfortable with the Four Ball Shower before attempting the five ball
To begin learning the Five Ball Shower it is helpful to first practice juggling the Four Ball Shower at a greater height than usual. This will train you to make more accurate throws, though the timing will be much slower than the full Five Ball Shower.
Practice this until your throws feel fairly consistent. To add in the fifth ball, start with three balls in your dominant hand and two balls in your non-dominant hand. Quickly make two very high (the exact height is up to you, but the higher the pattern the slower it will be) crossing throws from your dominant hand and then follow them up with two throw/horizontal pass combinations from your dominant and non-dominant hands respectively. You should make the last horizontal pass from your non-dominant hand just as the first ball thrown from your dominant hand is ready to be caught. As the throws from your dominant hand keep descending you will pass the balls caught by your non-dominant hand back to your dominant hand such that you end up with three balls in your dominant hand and two balls in your non-dominant hand (the same way you started).
You have just performed what is for all intents and purposes a flash of the Five Ball Shower (technically you only made four main catches so it isn't actually a flash). You should practice this until you can make all of the throws at roughly the same height with no collisions. After that you simply need to keep adding in more throws and passes as your skill level increases. The Five Ball Shower is very difficult trick, and it will take you quite a while to master it.