磁 literally just translates as magnetic/magnetism (and, apparently sometimes, in a stretch, “porcelain”). So going from “magnetic” to “attracting” then to “self-attracting,” etc. all has to happen with associations that only work in English.
That makes sense, though why then wasn’t it “masturbation magnet”? I’m guessing some text got deleted somewhere in the translation process, so it was trying to make sense of “マス 石.”
