3 year old DS said the F word

[obviouslyneedsupernanny]

"I hate my fucking shoes!"

I rarely swear and have no idea where he has heard this, how do I deal with it? He has repeated it twice since.

I told him it was a naughty word and that he mustn't say it again.. In hindsight I'm worried I made too big a deal out of it and now he will keep repeating

Watching. DD (6yo) had just learned this and taught it to my 4yo.

So bedtimes have now changed from - 'she called me a poopoo head' to 'she said I'm a fucking boy'