This site rules.
When I was 18 years old, I went to Europe for about a month or so. It was in a high school tour group with about 35 other people. We stayed at hostels that usually had any where from 4 to 8 beds in each room. The showers were usually the same as in locker rooms here in the US. So finding time to masturbate alone was almost impossible.
However 14 days in to the trip I was getting a little anxious about masturbating. I couldn't wait to find a private place to do it in. Suddenly we arrived in a bigger city and at a Hostel that had private showers in each room. So the next morning after eating an early breakfast, I returned to my room to find that the other three guys had all showered and were headed out to have breakfast. It was my turn to shower, so I quickly got in the shower.
Getting in to the shower I was hard in a matter of seconds. I knew that I would be left alone and nobody else would enter the shower. However, I didn't want to give in since most of the other guys had bragged that they hadn't done it since leaving the US. But I just couldn't take it anymore. I started stroking and it felt great. I leaned against the wall of the shower and stroked it as fast as I could.
Needless to say, I blew a huge thick load of cum after a minute of stroking. Probably the best solo session I ever had. After that I was able to do it a few more times before I got home.