This is a true story
When I was fifteen I went to my aunt and uncle's with the family for the fourth of July. My cousin is about a year and half younger than me. After the fireworks show everyone started to head out. My parents asked me if I would stay the night here so they could have some privacy at home. I said sure, whatever. My aunt put on a movie in the guest room for me and went to bed with my uncle. The door was shut behind her. I heard her talking with my cousin outside the door, because her bedroom was right next to the guest room. I heard my Aunt's door close and then the bed crunching under her enormous weight. Glad my cousin didn't take after her. My cousin was a redhead but had dyed her hair black. I heard the bathroom door open and then the shower turn on. As I was watching the movie, I got some fiendish ideas. The most appropriate of which seemed to be just opening my door so I could catch a glimpse of her as she walked to her bedroom. Maybe I'd get lucky and she wouldn't have a towel. I didn't want to pull an espionage mission and steal her towel so she didn't have a choice, because it seemed too risky. I thought about it anyway, and tried to open the bathroom door. It was locked. I knocked.
'What?' she said, clearly annoyed. She thought it was her mom bugging her.
'It's me,' I said. 'I gotta piss.'
I heard the door unlock and waited a moment. Nothing was said. 'Can I come in?'
'Yeah,' she called. I opened it and saw a flash of leg. She was clearly pretending to have just gotten back in. I didn't really have to piss so now I was a bit stumped. I flipped the toilet lid open and pulled out my dick, and I already had half a hard on. I just stood there, and thought she might peak her head out a bit if she were talking. I moved my right shoulder so my body was facing the shower more, and said 'So when are you crashing?' in a voice low enough that she wouldn't hear.
'What?' she asked.
'Don't be so loud, you'll wake them up.'
She poked her head out, and used the towel hanging next to the shower to wipe her face real quick. 'What?' she said. I saw her face tense up when she saw my dick in my hand and her head shot back into the shower.
'I was just asking when you're going to sleep.'
'I dunno.' she said.
'I'm just not tired. plus I still hear fireworks.' I still hadn't started pissing. In fact was just harder.
'Yeah, the neighbors still have a lot left.' she said.
'Yeah, I don't think I'll be able to sleep,' I said, more quiet than the running water so she couldn't hear again.
I heard her mumble something.
I mumbled nonsense on purpose and her head came back out, this time already looking down. She didn't look away from my dick as she asked 'What movie are you watching?'
'Some stupid kids movie,' I said, my cock now positively pulsing. I wouldn't doubt if I was an extra inch bigger than usual. She stared a second longer and then went back into the shower. I was very tempted to look inside, but thought she might tell someone. She's a manipulative bitch like that.
I decided I wasn't going to force pee out any time soon and flushed the toilet like I had anyway.
'I'll be in the guest room, if your still going to be up or whatever.'
She answered, but I didn't hear what because I was leaving the bathroom. I purposefully left the door cracked, and then the guest room cracked too. I was so stiff I immediately started jacking off on the bed. I decided to save it for when she got out. My plan was to ejaculate right when she stepped out into the hallway, so she could see me go off. But she shut the shower off a lot sooner than I expected. She came out and I started jacking vigorously so she would notice for sure. I saw her pause outside the door, and then with a quick knock she stepped in and turned on the light. I stopped jacking and sat up, staring at the TV. 'What's up.'
'Hey,' she said and sat on the bed, still in her towel. I lied and said she was blocking the TV a little bit. This was of course virtually impossible, since the TV was mounted higher than her head even if she was standing, but she said 'Sorry,' and scooted back until we were side by side. I made sure there was only a sheet hiding my dick, and let it lay against it so she could see it's shape and size. More than a few times I saw her looking at it and I wondered if she'd ever seen one before. We talked a bit and joked around, and once she called me an idiot or something to the equivalent, and I got her back by tickling her thigh. She laughed and bent forward, pressing her wet head against my chest trying not to laugh because her parents were sleeping.
'Stop, stop, you're making me laugh!' I moved up higher, pretending to be ignorant, and felt my fingers get a lot warmer. Her crotch was generating way more heat than the rest of her body. I started rubbing there hard and she kept silently laughing. I felt her body convulse twice, and I moved my chest back so her head slipped. She took the hint, and as I rubbed her puffy mound harder, she bent forward and I felt her hand touch my dick.
'What is that?' she squeezed out through fake laughter.
I just moved the sheet out of the way. It took about two minutes I'm guessing, with me fingering her roughly, and her jacking me with her suppressed groans. When I came I grabbed my dick and finished off, spraying her thigh with more cum than I'd ever seen coming out of my dick still. Since then me and my cousin have met places, but we rarely do anything like that anymore.