I have a few times. It's a bit scary, but soooo thrilling! I always make sure my two stallions are calm and relaxed and if they get spooked or show signs of discomfort, I ease off and let them calm down and if the mood is clear they want to be left alone, I just leave them be and use my dildos or pounce on my girlfriend. Hehe.
Also, the cum flow is rediculous! I have shit gag reflexes, so my blowjobs end up with me covered in cum and my gf love to poke fun at me over it. Still its fun having her lick it off of me and its very stimulating to have her do that to me. Both of our stallions are comfortable with me, so its rare that they get angsty or aggressive around me, but fuck do their thrusts hurt sometimes! I usually need like a good moment to collect myself after we have sex. Legs go numb and I just wanna stew on their cum being in me lol