A Japanese word for pervert. Shows explicit sexual pictures, movies, comics, and/or even games drawn in the Japanese animation style. Also in American usage, it more often refers to Japanese porn, especially in cartoons.
Simply its anime porn.
A common practice in hentai is to stretch the sex acts beyond the beyonds of normal human sex.
Zenas: "What are you doing Kristine?"
Jonathan: "Sigh, she's at it again"
Zenas: "Her fantasies through the internet is just not right"
Kristine: "What?! NO! I'm..I'm playing tetris!"
Jonathan & Zenas: "She's a hentai fanatic"