It started ...

I mean, really started when I was twelve years old. My parents had gone out of town for a week. I don't remember or care why anymore and I doubt I did then.
I was already at the point where I had begun sneaking around the house whenever I could be alone. Pawing through mom's underwear drawer. Trying on bras and high heels. Finding items I hoped she wouldn't miss, I began a tiny collection of my own. I had shoplifted a pair of panties (finally a pair of my own! I'd never felt right with hers, that was crossing a line. I knew it even then.), lacy little things. Soon, I graduated to nylons and mom's baskets of discarded fabric and old clothes. With them I fashioned skirts and tops for myself to parade and prance around in, in front of my parents' full-length bedroom window (also where I could see their cars approaching for a quick retreat to my room). I imagined myself so much more sexy and stylish than I'm sure I actually was.
But once my parents went out of town, I knew I'd have the chance to step things up even more. Mom left me and my brother in the care of Stacy, a pretty 17-year-old friend of the family that I'd been crushing on for years. Stacy was nice to us, especially my little brother. I'd been counting on that fact, hoping she would keep him and herself distracted with little kid crap; board games, Nintendo, whatever, while I went off to my room to "get sexy" as I called it. It took a few days. All I managed to get away with was shaving my legs. I had never done it before and for a whole day, the feeling under my pants of smooth, hairless legs was making me so horny. Plus after two nights of peeping on Stacy undressing and me sneaking late night peeks at the Sears bra ads, I was near my boiling point. I left Stacy and my brother downstairs, playing Monopoly and snuck into my parents room (where she was staying that week). I grabbed a pair of her used panties and a bra (and the full length mirror), ran them off to my room, stripped down and put the lingerie on.
I posed in the mirror like crazy, feeling my legs, pouting and prissing around. Then I got my balloon falsies from their hiding place. I noticed that Stacy's bra was smaller than mom's. Thinking of her tiny breasts made me even harder. I began to feel all over myself. My young, tiny cock tented the pretty peach colored panties. And I rubbed it. The satiny material (much smoother than the lace of my shoplifted panties) gave me a sensation that was so new and exciting. Positioning the mirror to face the bed, I got up on the mattress, straddling my pillow. I leaned forward, now on hands and knees. My pantied penis rubbing the pillow as i wiggled and thrust my hips across it over and over. The feeling on my dickie was so intense, made my ears hot, made my tummy tingle. "I'm sexy, I'm so sexy, i moaned. It was like the best feeling tickle ever. It made my stomach seem almost queasy, but it felt nothing but good. My eyes glazed as I watched myself grind the pillow. The zipping, swishing sound of my borrowed panties humping that pillow.
I leaned up, still slipping my penis against the pillow. I popped my thumb in my mouth and began to squeak and squeal. Upright now, humping the pillow. Still moaning, "I'm so sexy, I'm a girl .. a GIRL"
Then I heard it, a spurt noise. So loud it shocked me. Then two more. And just as I looked down, the sensation hit me. The tingles, the trembling, the overwhelming body sensation flood of my first orgasm. With no control. My penis simply shot burst after burst into her panties and I couldn't make it stop. The head still so sensitive as I pulled down Stacy's panties to watch my penis twitch the last few tiny drops of cum out. I simply stared in joy and excitement. Until it got really quiet. Too quiet in fact. I looked up from my daze at my bedroom door. Left cracked open in my haste. And I saw her shadow swiftly and almost noiselessly disappear like a shot down the hall and I heard her feet tiptoe back downstairs.
I cleaned up and went to bed (over an hour early) the next day we said nothing about it and the day after that my folks came home. I saw her many times after that, and strangely it was never uncomfortable. Maybe I imagined seeing her at all. Strange though that she had left another pair of panties and a bra in our basement laundry room the day she went back home. I always chocked it up to good luck on my part.