Seeing other stories about how mothers caught their sons masturbating or vice-versa reminded me of what happened when I was still in school.
Most mornings before school I would take the time to masturbate before I left because one, I did it every day anyway, and two, seeing all the hot girls all day long would make me want to cum, and taking care of it before helped slow down that process.
One particular morning I was in the middle of my session, really getting into it, and I guess I was taking a little longer than normal, because all of a sudden my door opened and my mom walked in asking if I was awake. I was completely naked, and even though she already saw me, I pulled my sheet over me, but it wouldn't have done any good since the tent was still there. She made a sharp gasp and said she was sorry, then backed out and closed the door behind her. I couldn't believe that she caught me and my cock deflated pretty quickly, but a few seconds later it swelled back up to its' full length, and I felt even hornier just because someone saw me, even if it was my own mother. I swung over and sat on the edge of my bed and stroked hard and fast, pulling a sock over my penis just in time to catch all my cum.
I took a few minutes to get dressed and ready, and when I went downstairs all my mom said was she would drive me to school. I usually walk, but there was no way I would make it in time today. The whole drive there was in silence until we pulled up, and she told me from now on she would knock and wait. All I could say was 'ok...thanks.' I went in and got to class just in time, but needless to say I couldn't exactly think straight and didn't get much work done that day.