Copyright: your resistance only makes my penis harder
A rather strange meme; refers to an animated hentai series, Words Worth, that featured a male anthropomorphic horse character who was also a rapist. One particular rape scene involving him had a line of dialogue that was to the effect of, "Keep struggling, it turns me on," which was infamously literally translated as: "Your resistance only makes my penis harder!"
Further information on the meme can be found here.