The shower is a private area for everybody (unless you decide to shower with another -hopefully special- person to save some water; because you know, climate change and all). But let's face it, we are more inclined to share our bed or bedroom with somebody else than we are willing to share our fun and private time in the shower, or in the bath (you are lucky if you have one).
We do such stupid sh*t in this private 'temple' of our own that we laugh at it ourselves when we reflect on it later. Let's see some classic and some more specific shower-action!