Mine happened maybe about 6 years ago with an SP that was known for her YMMV and restrictive service. She was a well know girl from Asservissante and everyone that reviewed her said she was very good looking but restrictive.
Knowing all this in advance I still booked her thinking I was gonna be the one that was going to change her restrictive ways. Well when she arrives she was just as advertised in her reviews, good looking, restrictive, lay there like a dead corsp. So I'm thinking, alright I'll do something with her I never done with an SP at the time. So I asked her if I could finish on her breast. She had no problem with that as long as it was below her head area. So I mounted her cowboy style and started working my johnson for the big money shot. I really held it in as long as I could before I shot my load and when I finally did the pressure that built up shot my load about 3 feet which was way past the intented target of her breast. Since she was looking down my cum shot landed right in her eye and on her face. I was like "Oops!, did I do that". She was very unhappy about this but it was unintentional on my part and when I tried to book her again 2 years later she refused.