My own experience with dropping trou in front of others became commonplace - especially after the military. In boot camp, you didn't even have time to think about it. You jumped out of bed, boner and all (cause nobody wore anything to sleep in), and sprinted to the gang shower. Nudity and boners were accepted without question.
As was jacking off
As a dancer I shared dressing rooms with the other men (some gay, some str8). You stripped down and pulled on your g-string dance strap and changed again after the show. Often times, we would help one another shave - no such thing as a hairy dancer - backs, balls, butt-cheeks, and butt-cracks.
(Ahh, what timing! A buddy who danced with me just called and invited me to breakfast. We had a short 2-month fling after, instead of the typical semi-boner everyone got (str8 dudes too!), I popped a huge, full hard-on as he lathered up my balls to shave me. Anyway, I shall return to finish this post.)
So, where was I? Parties during the summer, everyone would be naked in the pool or jacuzzi. Typically, one of the women and I would have be the first to doff the clothes. It never took long before the rest of the guests followed. Only once did a guy sprout a log of wood. And that happened only because his nude girlfriend deliberately caused it. He finally pushed her off, stood up with his cock as rigid as a telephone pole, and asked me for a towel. He (only slightly embarrassed by his hard-on) wrapped the towel around himself, went into the house, dressed, and left the party.
Our fears of other people seeing our wilted willies,