The shower is same pattern you've probably seen many times before in cartoons (and some of these cartoon characters can apparently do 10 in a shower!) Each object follows the exact same path as the object before it, namely, a circular path. The trace of a single object would reveal that it is thrown in an arc from the right hand to the left hand and then thrown directly across to the right hand. (If you are left handed, reverse the pattern so the left hand throws the arc to the right hand and the right throws directly to the left.) That's it. The right hand always throws arcs to the left and the left always throws directly to the right.