True story from a few years ago.
Like most boys in their late teens, I used to wank as often as humanly possible. I never had a lock on my bedroom door so I usually had to lock myself in the bathroom or wait until I went to bed before I could get myself off. Openly jacking in my room during daylight was a rare treat for when I had the house to myself.
Early one summer evening, my family had gone to a friend's house and I made a beeline for my room and the porno stash on my computer. I thought I had the house to myself but as I headed upstairs I heard pages turning in my younger brother's room. I carried on regardless and pushed my door shut behind me, knowing that he'd never enter without knocking. I turned my pc on and whipped my trousers off, gently stroking my balls while the computer loaded.
I began thinking about how, when I was my brother's age, I'd enjoyed finding my older brother's porn mags and thought it was sad that he'd never experience that same pleasure because my porn was password-protected. My cock started to swell as I imagined what it'd be like to catch him using my porn and see him pulling his dick. I knew it'd never happen but the idea turned me on way more than I expected.
A thought struck me. 'I wonder if my brother might enjoy catching me as much as I'd enjoy catching him?'
The thought made me ramrod stiff in an instant. I wrapped my hand around my cock and began to slide it back and forth slowly. The rush of pleasure made me feel bold, and I decided to let him 'catch' me enjoying my secret pastime. I fired up a porno image slideshow (no broadband back then, movies were hard to download) and stripped off my shirt so I was fully naked. As I sprawled on my bed, the early evening sun came through my window and I lay there for a moment enjoying it's warmth on my balls. Then I slowly opened my door...
My bed was right behind the door, so that when the door was opened the pillow end was hidden but the rest was visible from the hallway. My brother's door was next to mine but at a 90 degree angle, so he couldn't see into my room without entering the hall. My heart was pounding when I first moved my hand down to my cock knowing that he could walk out and see me at any moment. I stroked very slowly until I calmed down, fearing that I might blow my load before he caught me.
After a couple of minutes I was back in control, and was frustrated that he was still just reading in his room. I started to breathe heavily and loudly, almost moaning in an attempt to draw his attention away from his book. I stopped when I heard his bed creak gently, and I could barely hear his footsteps on the carpet as he moved slowly towards our doorways. I think he must've guessed what I was doing because he moved so quietly, stopping right in front of my door.
I had planned to act surprised and cover myself up once caught, but I had to pretend that I didn't know he was there until he disturbed me. He didn't. He just stood there looking. He could only see me from the chest down and I couldn't see him at all, so I continued to pretend I didn't know he was watching.
I ran my fingertips up my six-inch cock and the back down to the base, through my pubes onto my balls, gently tugging at my sack before repeating with the other hand. After a minute or two I eased my foreskin back to reveal my tip, slick with precum. I massaged it into the head of my cock with one hand while lightly squeezing my shaft with the other. I tried to imagine the thoughts going through my brother's head, seeing me playing with myself this way. He continued to watch silently so I concluded he must be liking it!
I tightened my grasp on my cock and began to wank more purposefully. I teased him with a soft moan to let him hear how much I was enjoying myself, though I'm sure he could see already. I moved my free hand across my inner thighs and over my balls, squeezing and fondling my scrotum with delight. A couple of minutes later I began rocking my ass up and down slowly, fucking my fist. With my other hand I gathered some precum from my dick and brought it to my mouth.
As I licked my fingers clean I glanced over at my computer screen, but the porn seemed so dull in comparison to performing for an audience. With that dirty idea in my mind, my nuts began to tighten and I approached orgasm.
I tried to slow my wanking to delay the inevitable, but I came and came hard. I shot several ropes of cum, higher than I ever did before and they splashed across my shoulder and chest. I kept cumming and it ran down my cock, over the back of my hand and into my bush.
I lay spent for a moment, holding my still-hard cock in my hand. I noticed my audience hadn't left and I realised he was probably more nervous than me at this moment. With a last act of exhibitionism, I climbed up from the bed right in front of the open door. It took a moment for him to realise that I was looking at him. His eyes quickly traced from my dick up the length of my naked body as I stood there exposed, my cum beginning to run down my chest.
Then I closed my door.