When I was in university our residence had split floors, where half was divided into 4 suites of single rooms with shared bath and toilet and half was apartments. The apartments were co-ed, but my part of the floor was all guys, so we were pretty laid back about clothing and such. One day, I was alone in my suite when I heard a woman's voice call my name. I was standing in the bathroom, taking a piss and wearing just boxers. I am a guy, and thought I was alone, so I left the door open. I answered the call and said, "Just a minute." I fully expected that whoever it was would wait until I came to the door and let her in. I had just given the shake and turned to pull up my boxers when one of the women from the apartments appeared in front of the bathroom door. I was off guard and paused as I faced the door, with my boxers still down and my cock just hanging there. I looked at her shocked expression, and she looked directly at my cock. It was my friend's roommate, who was 5 or 6 years older than I was. She got so embarassed that she ducked into the first open room. I wanted to get my clothes on so I quickly ducked into my room. Yup, she was standing right there in my room too. I pulled my pants on, and we had a laugh. A few weeks later she made an appearance at one of our parties and we fooled around a bit, but nothing serious came of it. I was just glad that I was having a good hang day, and thankful that I was not giving it a tug when she came in.