I had very much the same experience when I lived in an all male dorm. There were about 40 guys in two men rooms. We all shared a large latrine style restroom/open shower/sink facility at the end of the hall.
Many guys left their door to the hall open so that the ventilation could cool better. Nude visitors from the shower were a common occurrence. We all lived in our underwear most of the time. Very, very few guys were offended at the lifestyle to include other guys who came to visit from other all male dorms,, since that is how their dorm mates lived also.
Boners were not common, but semi turgid dicks could be seen frequently. One of my next-door neighbors would talk with his girl on the phone while nude or in his underwear, and stroke his rigid dick for extended periods of time. He did have the social grace to face away from the open door, but if he caught you looking, he would just shoot you the finger an thrust his dick in your direction.
Heterosexual porn mags were plentiful, even back in the 70-80’s, so if you wanted to see someone get a boner, just leave a few laying in easy reach in your room. Guys going to and from the shower would stop for a visit and leave with a boner. No one was offended if you offered to let them take the mag to the restroom so long as they didn’t get it wet. The common response was to drop their towel, give their hard dick a stroke or two in your direction, and then head off down the hall while holding on to their tenting towel.
Back then this behavior wasn’t crude, rude, or socially unacceptable. If anything it was an honored sign of acceptance and community. Where did it all go???