I'm going to break my sister's priceless toy
Why would you break her toy?
I want to keep her away from this bullshit toys.
That is something that brings her joy, you shouldn't destroy it. It is rude to intentionally destroy things that do not belong to you.
It's none of your business, my parents will be pleased when I do this.
I don't think your parents will be happy at all! Please consider dropping this plan and just leaving her toys alone.