It was back to school soon, so I took my Son out to get him new slacks for the year. While in the change room, I was helping my Son try on one after another; we were running late and in a hurry. I was helping him with his third try on, when I noticed he was getting hard. I helped him off with the slacks and told him to take his undies off too. He silently hesitated as I told him, "C'mon, sweetie, so we can get this done." I helped him slide them down to his ankles and told him to have a seat on the edge of the bench. I kneeled down in front of my Son and told him, "Now just relax and stay quiet while I help you out with this rage'r of yours, okay?" I took him in my mouth and started to work him up and down with my hand. He grew rock throbbing hard as he started saying, "Oh, Mom... I continued working him for about another minute until, suddenly, he started to grunt, grumble, and cum for me. He violently launched shot after shot of his warm cum in my mouth while I continued handing him off to suck him dry for all the rest. I was surprised; It was a lot for a kid his age. After he recovered a bit, I told him to get dressed and that we will get him clothes some other time. Aside for my Son thanking me for being so understanding - really - him, thanking me for his first blowjob, it was a nice quiet ride home...