This talk of swearing in front of the kids reminds me of a bed-time occurence a few months back. I was sitting on my Small Norm I's bed reading out loud, with Small Norm II sitting on the floor leaning against the bed. I leant forwards at the same time as she stood up, headbutting me right across the bridge of the nose.
I got instant stars and watering eyes, Small Norm II burst into tears because she thought that she'd "broken Daddy". The wife took her straight into her own room to calm her and I said, very calmly to my Small Norm I (who was 10) "Block your ears, please" before letting loose with one word very loudly.
Small Norm I's sniggering suggested that he hadn't blocked his ears very well but, given that he tells Mummy off for saying "Oh God!", I don't think he's going to be turning into a trooper for a couple of years.
A while back, Small Norm I came home from school complaining that a teacher had used "the c word". We were shocked but he wouldn't say any more. I was on the point of going and demanding the teacher's instant dismissal when the wife got him to open up. Apparently, his music teacher had said "electronic drums are crap", and that was the c word which had traumatised him.
Bless.