Communal Open Shower
In the locker room at the beach club I belong to there were 3 shower heads next to each other. Some of my friends wouldn't take off their bathing suits. I figured what the heck. That's the way it's done so...I was nude. As an adult at the same beach club they have separate showers in the locker room but everyone would still dry off, shave and use the hot tub or sauna nude. Now a member of the YMCA hardly anyone is nude and at club I used in North Carolina this past summer they had a sign in the locker room to stay clothed AT ALL TIMES in public as it might offend someone.
6th grade gym class, early 1970's. Showers were mandatory. Good thing too - I work in a K thru 8 now where not only don't the kids shower, they don't even have locker rooms or dress out for gym! These kids stink after an hour of physical activity!
Mine was as a 7th grader. My middle school gym teacher made us shower as part of our grade. It was half the class on Mon/Wed and the other half on Tue/Thu and optional on Friday. I remember being uncomfortable the first couple of days, but we got so used to it that we showered every day, even if it wasn't our day, and after sports practices.
Anybody that gets used to being seen naked at that age is over it for life!
My father introducedy my younger brother and me to showering at home with a group shower when we were about 6 and 8 yo. I think my mother was probably tired of cleaning the bathtub. But as far as showering in public, the first week of 7th grade after gym. I remember the teacher advising us about how you dry off from top down, don't dry your butt then your face--good advice 55 years later :-). Then it was daily during school time for the next 6 years and is still a frequent activity at gyms, pools, etc.
From middles school all the way through college and in Boy scouts too. All the showers were communal. All the way until college, the boy hormones kicked in when showering in public and most of the time, being young men we had to prove our prowess. By the time college came around, no one cared (me included) what state our manhood was in, infront of others.
When I was six my town built a new public pool with signs that stated that a nude soap shower was required by state law. So at least the adults obeyed but only that summer and ignored it afterwards. I remember they had a wringer for wet swimsuits and I took mine off to try it and got a boner as a result. The high school attendent stared at me in disbelief but I didn't have any shame or embarassment since no one had ever told me about erections, or anything about penises for that matter. A few years later in junior high I remember worrying I'd get an erection, but as it turned out I felt very comfortable naked and have enjoyed it since.