The whole point is generally to see what ideas you can come up with using the same word; while I agree it might be time to pick another word (perhaps something that requires a bit more creativity, or at least something that's not a body part, to avoid repeating similar things with a different word - otherwise you get cases like on the FFX board on GameFAQs where, without fail, the first suggestion posted in any topic of the kind is Seymour: "Feel my ____! Come, Anima!"), let's not just go generic.
As for the X-rated stuff, I think the general consensus here is that the majority, if not all, of the boards' users are mature enough that it's not going to be a problem. I would think posting it would be fine; maybe if you want to be careful, put a warning and hide it the same way we hide spoilers.