When I was 14-15 my mother was in a womens bowling league and would be gone every Monday between 8:30am and noon and I managed to be sick on those same days, strange I know. We had a backyard with a wooden privacy fence and I would strip naked and run around the back yard and peek into the neighbors yards hoping to see someone.
On the one side the neighbors yard was elevated and I would stand next to the fence and jackoff right in front of the kitchen window but alas nothing ever happened.
On the other side the neighbors yard was just a bit lower than ours and once I caught the lady out mowing so I pinned up a towel, for some reason I was afraid of being seen by her and I pulled out my dick and began to jackoff while watching her. I just happened to not be naked this time, don't remember why. I was going real good watching her boobs bounce as she approached the fence and just after I shot a massive load all over the towel and fence I turned to look over my shoulder and there stood my mother about 25 feet away.
I don't know how long she was there, but she couldn't help but to see the ropes of cum her son was shooting. I was flabergasted and embarrassed. I muttered something stupid, put my quickly deflating cock back into my pants and walked past her back into the house. She was just staring at the ground and to this day not a word has been spoken about it.