I will not say "Stupid"!

So, Campbell has said "Stupid!" a couple times in the last two days. I've had to start filtering some of the PG movies that sneak past us since we think they are just fun cartoons. Then they bust out with a word here and there ... stupid, crappy, butt .... you get the idea. I'm learning the difference between G and PG pretty quickly now! Anyways, when I get on to her for doing something that she shouldn't be doing, I always tell her to look at Mommy's face. If she doesn't look at me, she won't pay attention and she won't listen to what I'm saying. So, I keep telling her, "Look at Mommy's Face! We do NOT say 'stupid'. It's not a nice word. You will go to time out next time you say that!" She has now told us multiple times tonight, "Mommy, mommy, listen to my face! I will not say stupid, OK?" I am having such a hard time not laughing at her, so it's really not helping the situation. It really is pretty cute and funny when she says something like that!