At our family Christmas party I dared my gf to go knickerless. After a couple of drinks we both got frisky, so she sat me down and sat on my lap and rubbed her pussy into my cock until it was rock hard. We both noticed that her long flowing dress was covering everything up so she slipped my cock out of my pants and into her wet pussy. We then proceeded to gently shag in front of everyone. Several people came over (including her mum and dad) to chat to us which turned me on more and got my cock even bigger. We didn't think anybody noticed but her sister commented the next day that it had been fairly obvious. That just made it better! Can't wait for next year!