Impregnation, where one character impregnates another. Around here it often refers to alien monsters, who only need a short time to incubate in a human womb before they can be born. However, very often the birth isn't actually shown; I know a lot of people are interested in the idea of impregnation, but they don't care about the actual birth.

I'm a big fan as long as it's tentacles/demons/monsters doing the impregnating

i agree with scarlet.

That's interesting, because I have met a couple of people who are interested in "regular" impregnation...

Still, around "here" I suppose it would be more likely to be the, ah, interspecies sort of impregnation?