Oh, I so know how you feel there. My DS3 run up to me the other day with a toy Mack (The truck from cars) and declares. "Mum, a f***".

He also does "ah s***" when his blocks fall down. *sigh*

Unfortunately, he learnt the second one from all over the place. I have been known to cuss when I kick my toe - which I do with gay abandon these days. O.o DD1 has started trying to be all grown up through expletives. Then there is tv. I am wondering if there is any point trying to stop it. Its rampant at school. Only DD2 finds it all distasteful.