Usually, this is done in the porn industry where the male actor would appear to ejaculate inside of the woman's vagina, or in rare cases, anus. However, don't fool yourself into thinking that this is actually real semen flowing out of the woman's vagina. There is a hidden scene change in the middle of the sexual intercourse where they would fill the vagina with milk or any substance that resembles semen. Of course, this is often done unprofessionally and any person with a quick eye can see that hidden scene change.
I was watching this porno and the man had an orgasm inside of the woman. I became unaroused at that scene because it was so obvious that they had faked it, it didn't even looked as if the director had tried to make the creampie look real.