I have a three year old who quite often whips out the "Jesus Christ!" when something doesn't go his way - though his father has tried to limit the damage somewhat by insisting it's "cheese and rice!"
And one of the teachers at daycare was furious with my two year old, darling girl who would say "whatever" with exactly the right intonation, in exactly the right circumstances. What was even funnier was when the teacher "tattled" to the head of the daycare (seriously, who does that?) the head was like "oh yeah - she's been doing that since she was 15 months old" Snicker. Bad Daddy.