The act of sexually assaulting a woman with tentacles. Since no human being can really sprout tentacles, this is generally restricted to Japanese Hentai. A versatile entity, such as a robot or alien, can perform tentacle rape on multiple victims at the same time.
Guy: you're a freaky slut aren't you
Girl: yea baby, give it to me
<Guy sprouts tentacles and rapes her orfices>