Looking for some advice on our 5 year old's most recent behavior...

We have taught her words like stupid, hate, dumb, etc. are not acceptable to use or say to someone because they are hurtful. For the longest time, she would say them regardless, and I think that was the start of her testing limits. We told her we didn't want to hear those words and she needed to think about what she was saying before she said it. Now, instead of using the word in context, she says "I was about to say 'stupid' but I stopped myself." She does this multiple times a day. It is like she is obsessed with saying the words in any way she can.

She does this with things she knows she is not supposed to do, too. She will either do them and then tell us she did it, or she will tell us she thought about doing it but she didn't.

I feel like she is so "negative" lately... meaning, she wants to say and do the things she is not supposed to. I have tried explaining why we tell her not to do those certain things (it hurts others feelings, it keeps you safe, etc.) so there is meaning behind our rules, but it really doesn't seem to help. Anyone have any advice?