It was freezing in the tent. Never mind how hot and sunny it had been that afternoon, this high up in these old mountains the temperature had plummeted. I muttered another curse at my parents and tried to dig myself deeper into my sleeping bag.
"Are you still awake too?" The whispered voice belonged to my little sister Sal. Well, I call her little because I'm a foot taller than she is, but we're twins. Just finished school and dragged off by our parents for one last family camping trip before we both went off to uni.
"Yeah," I whispered back. "It's freezing."
"Told you you'd need a bigger size sleeping bag." She was right, of course. My old bag used to be fine when I was fifteen, but I'd grown since then. I was regretting being too lazy to buy a new one.
"You seem to be cold too." I'd caught a hint of chattering teeth. "Not sure it would have helped." We were both dressed for sleeping in large T-shirts and our underwear. Not enough to provide much warmth.
In the end we came up with the old solution of zipping our bags together and combining our body heat. It was a bit awkward in the confines of the tent, particularly because we didn't want to wake Mum and Dad, whose tent was a few yards away.
But we managed it, and Sal pressed her back against my chest. "This is better already," she whispered. She was shivering a little, so I put my arm around her and pulled her close. She was right: I was feeling warmer too.
It didn't take long for me to fall asleep, the fresh air and the exhaustion from the day's long hike finally getting the better of me.
When I woke it was like surfacing from a deep, black pool of icy water. I knew I was waking up, but it took me an age to actually get there. When I did, I realised my arm was still around my little sister, her back and arse still pressed against me.
And my cock was like a shaft of molten steel pressing back against her.
Nothing unusual about waking up with a raging boner, of course. It's only strange when you happen to be sharing a sleeping bag with your sister.
I fought to open my eyes, hoping that it was morning and I could get up before Sal woke. Unfortunately it was as black as midnight. The air in the tent was still freezing too.
I must have moved more than I wanted, because Sal's steady breathing stopped for a moment and she gave a twitch. "What time is it?" she murmured.
"Still night," I whispered. "Go back to sleep."
A grunt was her only reply, and I waited for her breathing to become deep and regular again, hoping that she wouldn't notice the hot, hard rod pressing against her crack.
No such luck. "What's that?" she whispered.
"What?" I cringed inside.
She bucked her arse against me. "That."
"Morning erection. Sorry."
"Make it go away. I want to sleep."
I gave a frustrated laugh. "I would if I could. It's not something I can control."
In fact I was harder than ever. I might have concerns about who the firm arse belong to, but my cock didn't.
"Shit." Sal sounded more awake now. "How do you normally get rid of it?"
Normally I'd have a wank before getting out of bed, but I wasn't going to tell her that. "I just ignore it until it goes down. You know, think of other things."
"Alright then. Think of other things. Where are we supposed to be going tomorrow?"
I thought for a moment. "There's supposed to be a pretty waterfall. King Arthur's Beard, or something."
"Stupid name." Sal wasn't one for romantic legends.
"I suppose they couldn't call it King Arthur's First Piss of the Day."
That brought a muffled laugh from her. "King Arthur's Late Night Piss After a Visit to the Pub."
I felt her body shake as we both tried to stifle our laughter. Unfortunately this just excited my cock even more.
Sal seemed to notice. "I felt it twitch! It's not going away, is it?"