Samantha jumped as the sudden electric shock hit her cunny lips and she couldn't help letting out a small yelp. Immediately there was an answering cry from her twin sister Sandy and again a shock coursed through her sensitive labia, but this time she was ready for it and managed to bite back another yell.

She looked over at Sandy and mouthed "I'm sorry".

"I'm sorry too" Sandy mouthed back, "it was my fault".

Samantha nodded, but gave her twin a brave smile, she could hardly blame her sister when she was trapped on what daddy called his "One Bar Prison".

It was a simple but effective way of making sure the girl wasn't going anywhere, a metal rod was attached to the floor with a dildo fitted to the top. The naked 10 year old had had to stand on tip-toes astride it whilst daddy extended the rod upwards until the dildo was securely in her cunny meaning that there was no way she could lift herself off it. Not only that, but a sensor was then put under each of her heels such that if she dropped down off her tip-toes it would complete a circuit and give her a shock through the clamps on her pussy lips.

Samantha, meanwhile, equally naked was spread-eagled against a X-shaped cross which was tilted backwards. Normally she would have been able to relax and lean back against the cross, but this time there was a pressure sensor behind her bottom such that if she touched it, she would get a shock. This meant that she had to spend her time with her hips pushed forward, displaying her bare cunny completely.

That wasn't even the worst part, though. Doing something that meant you got a shock wasn't nice, however each girl also had a very sensitive microphone next to her mouth such that the slightest noise would give a shock to the other girl! This meant that they couldn't even communicate in whispers, but could only shape words with their mouth and try not to make a sound when, inevitably, they triggered the shockers.

Daddy sometimes called this Pain Ping Pong, when they'd first started playing like this he'd give one girl a smack to make her cry out which would give the other girl a shock so she would cry out too which would cause another shock and so on until one of them finally managed to stay quiet. These days they were better at keeping the noises in, but daddy had just turned the shockers up higher!

They knew they were safe because daddy would be watching everything through the cameras he'd installed and trained on their naked bodies and he would, of course, eventually come back into the punishment room and let them off the torture devices. Then there would be lots of kissing and cuddling and touching before he fucked one of them and licked the other until they came, but neither of them knew how long that was going to be...