Another mom incident ...
I've only been caught once. Sure enough, it was my mom.
I was 16 and was humping a pillow to Petra Verkaik's centerfold. Mom didn't knock, came in, placed some papers on my desk and started to walk out. Then she looked back and just stared at me from behind for about 5 seconds -- probably in disbelief. Total Freudian-type moment -- something I didn't fully realize until later.
I finally said, "do you mind?" She walked out, not bothering to even close the door, totally embarrassed but giggling at the same time.
Years later, when she first met my wife (to be in another 3 years) the two weeks after I first met her. My mother started talking about the tight ass I had as a teenager (I was 40lbs. heavier when I met my wife -- 5'9" with a 28" waist and an athlete's body at 16-17). I never thought much of it and told my wife my mother was just trying to bait her by talking about my ass -- to get my wife (again, only a 2 week girlfriend and not yet even steady at the time), to assume my mother was open to talking about it and get her to tell her everything.
Although my wife agreed with me, she said my mother really poured it on. My mother made comparisons to how tight (and hairy) my father's ass was when she first met my father, etc... and how I took after him (and other things, like how my ass would lose its hair over time, something she seemed to miss). I guess I was very much like my father when he was younger -- and I was the first (and clearly the athlete) of the boys. That one time was the only time my mother ever saw my bare ass in full form in my teenage years. So it's safe to say that the conversation with my wife made me freak out for days, even though it was 4 years after the incident, and my wife couldn't even hold me as a result.
It's funny, because the incident itself didn't bother me right after it happened -- I got off on Petra in no time. But thinking about it again, when I was 21, I couldn't get it up for days!
