Back in grade 10 when I was 15 I had a big crush on a Greek girl named A, she had gone to my elementary school. She was cute but quiet and relatively flat. During grade nine I noticed her chest was developing and then when grade 10 started I had a couple of classes with her and realized how she had matured and how beautiful she was. My step brother D who was in grade eight happened to be best friends with her little brother C.
One day D told me that C was coming over and he had something cool to show us. When he came over we went in D's room and he pulled out of his backpack a pair of panties and a bra. We all knew whose they were C knew I really liked his sister. I quickly snatched the bra out of his hand and read the tag 36D I and often fantasized about what their actual size was. D was sniffing the panties. Meanwhile we had all developed hard dicks which were obvious under our pants. C stated what we were all thinking and said do you want to jerk off with this stuff before I have to return it. Next thing I knew we all had our cocks out stroking. D had the panties wrapped around his dick and I had my cock in one of the bra cups, the silk felt so good on my cock. Having A's bra and seeing erect cocks for the first time was too much to handle I came first with D right behind me and C shortly after.
After we caught our breath we started talking about how often we jerked off and before we knew it we were hard again. C saw a ruler on D's desk and said let's measure ourselves. I think he just wanted to point out the fact that he was thicker than us. At least I was the longest I was six inches long and five inches round. C was only five inches long but five and a half inches round, D was five and a quarter inches long and after measuring twice we determined he was slightly bigger round. Which was embarrassing even though he was sort of a pudgy kid he was my little brother and because of his late birthday had just turned 13 and I was almost 16. After the measuring we jerked off again, this time I used the panties.