Communal showers are commonplace in sports venues, and some hostels. To be in one is a good way to mingle with other males: we all have a penis, so why try and hide. If another male offers to wash your back, I would accept the offer willingly.
This looks like an outside shower. I could be wrong, its the stone wall and plants that give that impression. Now who wouldn’t want to be showering when there are two males like this.
Now this is what I call a deep clean of the anus by another male who willingly ensures the anus is thoroughly washed. The erect penis indicates he is very happy providing this service to another male.