First of all let me say that I'm bi-curious.
I have a small one so I like to compare.
During a business trip in Korea I went in a Sauna (without having previous experience). I found out that when you enter a (all men) Korean sauna you first have to pass by the common locker room and must undress completely . There are only small towels for customers that barely cover half ass.
This fact was quite embarrassing.
Inside there was a large common room with 4 pools, 4 saunas (all at different temperatures) and all around the showers that must be used before diving in one of the pools. Everything is done in common and of course completely naked, but everybody seems to ignore the others. The people were mostly local but there were also some Western like me (between 25 and 40 yo) that seemed to know very well the place.
I spent 50 minutes in the swimming pools and I tried one sauna. When the thing started to become boring, I decided to explore the rest of the place: on the second floor there were: one smoking area (naked of course), the beauty salon, massage room and a TV room while close to a further corridor there was a signal for the so-called "sl**ping room". I entered and found a large room lit only by blue lights, where guests were apparently resting or sl**ping laid on mats.
I followed their example and laid as well, covering my dick with the towel. When after few minutes my eyes became accustomed to the darkness I discovered that some people were moving in the darkest corners of the room. It was easy to understand that some of the guests were touching each other. In particular one western guy was jacking off one young Korean boy while sucking his nipple. On an other corner an other guy was rubbing his dick between the legs of an other guest. Every 10 minutes some of the guys changed places and approach new guests. All the actions were limited to HJ. Only for few seconds one Korean guy with a very small dick sucked one fat man . It seamed to me that the man cum quickly.
I have seen almost 10 guys cumming.
I stayed for about 60 minutes refusing a couple of approach. I remained soft (probably due to the embarrassing situation) but inside I felt really turned on.