No, not really. At 3 or 4 my daughter shared with a sense of horror that another child has used the "S word at preschool. Since we had never used the word, I thought I better explain how inappropriate it is, however I luckily sought a little clarification from her first. It turned out that the "S word" was "stupid".
If parents don't curse, toddlers don't curse... Unless they are around toddlers that do.
LOL. I had the same experience, listening to my 4 year old twins argue with each other in the car about the "S" word...
Twin 1: You don't even know what the S-word is!
Twin 2: Yes I do!
Twin 1: Then what is it?
Twin 2:I'm not gonna say it...it's BAD!
Twin 1:I bet you don't even know it
Twin 2: Yes I do! But it's really really BAD!
Twin 1: OK, if you know it...then what is it?
Twin 2 leans in close and whispers....."Stuuuuupid"