I'm going to snitch on my 13 year old sister for what she has done.
Why do you think that it is okay to snitch on her?
I am afraid she'll eat the last piece of chocolate before I do so.
You are really going to snitch on your sister over some chocolate? I think that you should reconsider, it seems a little weird to tattle over something as miniscule as chocolate.
WTF I'm just joking she's such a bitch, I'd probably tell if on her anyway, she pisses me off.
You need to try to get along with your sister better and stop trying to get her into trouble.