There are many things that polite society deems to be "private" activities or actions, so doing those in public can be shocking, but definitely rude! Many of these things are learned restraints, but not everyone is taught that some things are private. The illegal activities, yes, but I guess not everyone's mother taught them to not, oh, let's see, pick your nose, scratch your privates, masturbate, repeatedly snort snot (versus using a tissue to deal with the problem), and so on. I am further convinced that many people who are offensive (or even simply annoying) have no clue that they are bothering others. I try to refrain from "mothering", but have tried to politely suggest that someone cease an annoying or rude behavior by offering a solution...

yeah that jerking off in full sight seems to get me everytime no matter the size of the room. THat reminds me of the time I was walking in the woods with my great dane. SHe was a great guardian-did it with humor. I looked up the stream I was crossing and there was a guy there doing that a little up the way. It surprised him when I ran up there with my dog and she let him know my opinion.

I don't like it when someone doesnt blow their nose when they need to and just snort

People talking on the phone while ordering food in the drive-thru or when they are at the front counter.

What the hell? Yah a guy beating off in front of you in the sauna is beyond irritating, it's illegal. I have to admit it took me off guard. The story was presented as a look into little things people do that are annoying, and then bam, it's about someone masturbating in front of people.

Haha yah had the same I was working at Walmart at the time and it was around 7am so I hit the bathroom before work and I herd this lady having phone sex in the stall- wtf! Why? Needless to say I got the hell out of there lol and people of Walmart.com is no joke-

That's bizarre... I've been hitting the schvitz for decades, never saw anyone rubbing one out at 185 degrees. Frequently see people do their breathing routines.

My own public pet peeve is people moving while on their phone.

Is this for real ? I assume then, this sauna is in a gym, or some public place ? For the guy doing the heavy breathing - I'd ask him why he's breathing that way - if you know it may not bother you so much.
As for Mr. Jerk-off, I'd go to the manager and tell him or her what's going on. That's not cool.

Try a different establishment.