LMAO - one of my brother's first words was the s-word.

I think it is a stage that all little children go through, and maybe it's too early for discipline relevant to it? I'm not sure as I am yet to be there.

Close though, DS loves the word 'Duck'... if i don't watch my mouth, I know what's next.

FWIW my memory of Childcare Education is not to reprimand; "You are Naughty", but to use the I feel statements. At his age and his level of understanding you could probably do that. "I feel ___ when you ___".

L, Mummy feels upset when you use words like that, followed by maybe you could try taking away a toy, puzzle, game that makes him upset (within reason) so he understands?