For all 3 of mine I've always just said 'I don't like that word and we don't use it in this house'. No one has ever questioned it, oddly enough and didn't keep saying it. The only one we actually had to discuss was dd1 started saying God a lot in K and we had to explain that it hurts Gods feelings to use his name like that and to please say gosh instead. Once she knew our reasoning and was given a substitute word she stopped using it.
My kids might be in the minority in being so easy to stop using certain words. I could see some personalities using it more just to annoy you. I don't have a good answer for those personalities.