Pornography has the problem of representing the unrepresentable - that is, trying to capture intimate sexual activities on film or video. Over the last several decades, pornography producers have tried to capture this "unrepresentable" element by making more and more "explicit" depictions that include close-ups of genitals, penetration, and ejaculation.
Pornography film producers fetishize the "come shot", which can be seen in the existence of compilations of ejaculation scenes and in the inclusion of replays of the ejaculation sequence in some pornographic films. In order for viewers of pornography to be able to view the ejaculation, the pornographic actor must not ejaculate within the sexual partner. In the slang of the pornography subculture, an internal ejaculation is termed a creampie.
When the "cum shot" was first popularized in pornography in the 1960s, it usually involved the man ejaculating near the woman's vulva or on the small of her back depending on the sexual position. Since the 1990s, a "cum shot" is often just refered to a man ejaculating on someone or something. Sometimes a cum shot is received on the face of the recipient (referred to as a facial). However, ejaculations on or near the breasts, anus, penis or vulva still occur.
The "cum shot" adds a sense of realism to pornographic films, because unlike other aspects of the pornographic depiction, such as facial expressions or dialogue, it is a physiological response and therefore it cannot be faked (at least not without resorting to prosthetics and special effects). The ejaculation scene also performs a closure role in the simple narrative form of pornography.