Tattle
When someone especially someone you know tells an authority figure usually a teacher or leader of a group of kids, that you are doing something you shouldn't be doing, if what you are doing is wrong, but isn't hurting anyone else, if someone reports you, they are a tattle tale, or a snitch.
Example:
Mark: Mrs. Murphy, Tom is on his phone and he knows he shouldn't be
Tom: Why do you have to tattle?
Snitch Squealer
Mark: Mrs. Murphy, Tom is on his phone and he knows he shouldn't be
Tom: Why do you have to tattle?
Snitch Squealer