Quite the unrealistic tag here, but basically having something go from either orifice, through the body, and coming out the other end. This is sometimes used in tentacle hentai, but some of the stories listed here, use it by having a person ejaculating through the entire body of another (yes, I know this is fucked up lol). A rather interesting turn happens, when the tentacles, or whatever else is going through everything, aren’t removed from the body.
An artist who often makes use of this is Jokerkin, where some kind of tentacle-parasite is placed through the entire body of a victim. They luckily also often feature Living Clothes.