Nothing comes to mind as far as stories, but I recently watch a video along those lines. Was by missbehavin26 and, at least on the site I found it on, called 'mom humiliates son with bully'. It was 20 minutes long or so. It only has her & a dildo (nobody as her son or the bully) but she does a pretty good job with the roleplay acting. The 'plot' was that the bully was invited over for dinner so that things can get straightened out, son gets sent out to get some food, and mom fucks the 'bully' (dildo).