When i was living on campus, the living arrangements were about 20 rooms per floor, sharing a bathroom (3 shower stalls, and 3 toilet stalls). So we didn't have our own bathrooms in our rooms. We were all pretty close friends on the floor (coed, both guys and girls) so during the day most people would have their doors opened, even if they were out. I found that the only times i could really jerk off was at night. I'd just tell everyone that i was going to sleep, and then just lock the door and start jackin. that was probably the only time i could have done it nude. But clean up was a bitch. I'd usually just shoot my load onto my stomach and then clean up with tissues.
i had a can of air freshner in my room so i just used that to mask the smell of cum.
Other times if its pretty quiet in the afternoon, i'd have my door closed and locked and start watching a bit of porn and jerkin off. But usually i'd just jerk off in my boxers. I haven't been caught before but people have knocked on my door immediately after i've cum, or in the middle of me j/o which means that i had to readjust myself and hide my boner before i opened the door.
I moved out in my third year with a coupel of mates. i shared a room with one guy. I didn't really pay much attention to his j/o habits, but i usually did it in the showers. I don't think he really noticed too much because i take long showers regardless of whether i j/o or not. one time however because my roomate is usually downstairs most of the time, i stayed upstairs and was watchin some porn and jerkin off. i had the door slightly ajar so i could hear him when he comes up. but as i got down to business i forgot about it (our door has no lock btw), and also because he was really stealthy when he came up. he didn't make any sound at all. just as i came, hands down in pants, porn on the screen, he came in. i was there furiously clicking away at the mouse to close everything with one hand still down my pants. lol he didn't say anything about it. just walked in, grabbed some stuff and walked out. Later i learnt that he didn't notice anything because he had just woken up from a nap and wasn't completely awake. thank god. lol.
and another time, because he usually sleeps a lot earlier than me, i was laying on my bed with my laptop, and decided to just whip it out and start jerkin. i thought he would've woken up and saw me, but he didnt. :-D