I traded "crap" for all my favorite swear words when I had kids, trying to set a good example. Ok, I was just trying to set a slightly better example and I do not always succeed. DD16 was about three and I heard her drop something in the next room and say "sh*t". That was why I tried to stop. Funny thing, my kids don't cuss (except for that one slip when dd was three lol) and obviously it isn't because they haven't heard the words. I think it is part of them differentiating themselves from me. If mom does it then it can't be that cool or whatever. DD8 gets on my case when I do it, complete with eye rolls.