A couple of months into a relationship with my first serious girlfriend (in which she gave me frequent blowjobs), she had done something or other to make me angry at her. She admittedly didn't enjoy swallowing, and never had done it. But toward the end of the blowjob she could tell I was getting close and kept asking if I was coming. I told her no even though I was and came in her mouth. The look on her face of complete surprise kept me laughing for at least half an hour after it happened. She was upset, but as far as I was concerned it was the funniest thing in the world.