I'm thinking of snitching on my coworker
What did they do that you would need to snitch on them about?
I think he and my boss are running a scam on their company.
Unless you have proof you may want to wait to tell someone. It could hurt their reputations as well as yours if you are wrong.
It's okay, I can prove it.
Then report it and do it soon.   It you could stop people from getting hurt by a scam, then your actions will be heroic.