Just going at it right now.
Today I was in the library of our university. I am currently studying for an exam and sometimes relieve myself in the toilet compartments. Today, as I was taking a leak, I started to get hard and thought about having a quick wank. I did not bother to leave the urinal and started to stroke fast and hard. After about three minutes I felt my orgasm come. Just at this moment the door opens, and I immediately put my dick back in the pants just in the moment I came! I think the other guy did not notice, as he hurried just to take a paper to blow his nose... or maybe he did notice, who knows. I washed my hand with my knees trembling and went back to my studies after cleaning up the mess in my pants a little.