When my children were very small I made up (or borrowed) words that felt like swear words to me for use in front of the very, very young. Like shazbat (borrowed I think from Mork and Mindy) and bordigals (acquired from Rodie Sudbery).It lasted fairly well for a few years but then I slipped back into bad habits. In fact when my youngest son was 7 he regaled us with a list of all the rude words he knew such as "the F word" "the S word" etc. We were baffled for some time by the "R word" but it turned out to be arse. A particular favourite of mine.