In college, my dorm roommate and I occasionally saw each other's morning wood. We both joined the same fraternity and roomed together there, as well. The fraternity house had gang showers, and my roommate and occasionally discussed having seen other guys in the showers with morning wood. Two guys in particular, were very well-hung - the reason for us to comment to each other. Now (pre-pandemic, of course), I occasionally see guys in the showers at my gym that appear to be a bit fluffed up. Finally, when I visit nude resorts and beaches, invariably I see a guy or two with an erection.
In reading through this topic, I note that a few guys wonder whether it is "acceptable" for grown men to be erect around one another. While it may not be that common for men to be erect around one another outside of purely sexual situations, I have to wonder why a guy or guys would allow others to determine what is "acceptable" for him (or them). Obviously, it's a good idea to be judicious in approaching the topic with other men, or just boning up in front of them - you may not want to surprise one of your buddies without testing the waters first. On the other hand, if you're sharing a hotel room with a buddy and you get out of bed with a morning boner to take a leak, it just shouldn't be that big of a deal. Just act like it's normal because, well, it is.