In one dorm I used to live in, the bathroom stalls were parallel to the shower stalls, about 4-5 feet away, so it wasn't uncommon to see guys hang up their towel, then walk to the toilets nude and back. The dorms I live in now aren't like that, as the toilets are showers are in separate areas, but I'll still do the walk naked if it's late at night. I've been caught twice, both with the same setup: I stripped off my towel and hung it up at the shower stall with someone using the adjacent one, then decided to use the toilet. While I was still in the stall, the other guy finished his shower and moved on to brushing his teeth at the sink. I had nothing to cover up with and started getting a semi; I had to pass by the sinks (and mirrors!) to get to the showers, so I just walked out like that, with one hand casually holding down the head of my cock.
The first time, the other guy spotted me and said "hey", and I replied back. I went up to the sink two over from him and washed my hands, revealing my semi in the process, then proceeded to shower. The second time, a different guy was combing his hair at the middle sink, so I had to walk up right next to him naked. I apologized, explaining that I thought I was alone. He smiled and said, "No worries, it's a bathroom." That got me instantly hard, so I bent over a little more at the sinks to partially conceal my boner, then went on to shower. No physical interactions ever took place, but it was pretty hot to be seen naked and separated from anything to cover up with.