I have a roommate in a one room flat we rent. We are good friends but never masturbated together or even dealing too much with the topic. I do it every morning in the shower and sometimes late evening when I think he is already sleeping. I didn´t know much about his habits, even though he might have figured out I do it often, he didn´t mention. The other day he was spending really a huge time in the bathroom and it was very obvious what he was doing. I was quite horny too so I went to the living room, unzipped my pants and started jerking off too. I thought I would have time enough to cum in private but at one point he opened the bathroom door and as it is just facing the room door, he caught me. He went out, I took my time and then we made an agreement that when one does it in the bathroom the other one could use the kitchen, the sign will be the closed door, because there is no key. Several times I thought when the bathroom was free, nothing is going on. I opened the kitchen door and caught him jerking there, so I found he does it maybe more often than me. Now I always ask when going there and so does he, even it became less and less taboo, last time he forgot to close the door. I found we spend quite a time masturbating.
I used to live in the college, six people in two rooms were sharing one bathroom with toilet. The shower was the official masturbation place, it has some kind of curtain and when it was occupied and somebody wanted to piss it was agreed just to knock and go there. Because of this habit we all were very well informed about when and how often each of us jerk off. When we were studying in our rooms we always saw room mates with red colour on their faces referring what they were doing right before. First I had a problem with that, but later I found it very free, just to sit in the shower, cover it and do not mind what do people around. I think we all masturbated just every time when taking the shower.