OP

Short for Cop

If you're being called an Op you probably snitched on them or told a secret.

Being called an Op is not a good thing, it means you betrayed their trust and they're probably angry with you.

Person One: Yeah, I accidentally told my mom that you broke her TV...
Person Two: Seriously Op? Now she gonna tell my mom. I'm gonna get my ass whooped.

Person One: I'm so sorry bro