Grammy and granda caught

This happened a while ago, but it's so vivid in my memory that I'll write it as if it happened last weekend.

I'm still in a state of shock; over the weekend, my granddaughter caught my wife and I fooling around on the sofa! We had started off cuddling, then I slipped her dress off her shoulders and pulled it down to expose her breasts, and she unfastened my jeans and pulled them down to my knees. As she began rubbing her gorgeous DD tits over my cock and balls, I was soon rock hard and she began wanking me. AS we got more aroused, she leaned over to suck my cock. She was sucking hard and noisily, and I was moaning and encouraging her to get my cock down her throat, so we didn't hear our 14 year old granddaughter coming in through the back door. The first we knew about it was when she exclaimed, 'Granda!!' I looked up in alarm to see her standing in the doorway with her mouth and eyes wide open. In a panic, Jane, my wife, sat up and tried to get her dress pulled back up over her naked breasts, but it hadn't been unfastened and so she was struggling to try and squeeze them back in. Meanwhile, I was frantically, trying to pull my pants and jeans up without trapping my genitals.
Just then, Jessica, our granddaughter, called out, 'no, stop! Just leave things like they are!' Shocked as we were, we just sat there like naughty children while Jessica walked over to us. She stood and coolly stared at our exposed bodies. 'God, grammy, what were you doing to granda?' Jane mumbled that we were playing grown-up games and that we should get covered up. 'Has mum seen you and granda doing this before?' 'Good god no!' exclaimed Jane. 'Well, I don't think she'll be very impressed when I ask her what grammy and granda were doing when I called to visit.' 'But it was an accident,' I cried out, 'We never knew you were there!''Maybe mum will believe that, maybe she won't. Anyway, you sounded like you were both having fun when I came in so why not just carry on, then I'll be an accessory,' she giggled. 'Jessica, you can't be serious,' Jane said. 'Lie back and pull your pants down granda,' Jessica said, firmly, 'and you can pull your dress back down grammy.'
Jane and I looked at each other in shock. Then, with a raise of her eyebrows, Jane pulled her dress down to her waist and I followed suit with my jeans and pants. 'Oh, poor granda's willy's gone all soft now, can you make it hard again grammy?' Jessica sat down next to us and watched closely as Jane bent over and rubbed my genitals with her bare breasts. Despite the shame and embarrassment of the situation, my cock responded and stiffened. Jane wanked me again as Jessica eagerly leaned forward. 'I'm sure I heard granda telling you to get that thing down your throat grammy.' Blushing, Jane meekly said, 'yes darling,' and bent over to take my cock in her mouth. After a few seconds of sucking, she was drawing it in deeper and deeper. 'Grammy, how the fuck can you get all of that into your mouth?' It struck me that I'd never heard Jessica use the f-word before, and the first time was now while she was watching her grammy deep throat me!
Just then, I gave an extra little thrust of my hips and Jane began to gag, pulling her head up and coughing saliva and pre-cum all over my cock. 'It's OK,' she gasped to Jessica who had sat up in alarm. 'It just takes practice, but sometimes there's more cock than you can take.' 'And do you actually like it grammy?' Jessica asked with a concerned look. With a wicked grin as she lowered her head to start again, Jane said, ' I absolutely love it, sweetheart, and I bet you will too when you get older.'
From the look on Jessica's face and the way she licked her lips, I didn't think she would be much older before she tried sucking cock.