What is the most “stab in the back” thing that happened to you in residency

For me I’m paranoid that my co-resident told my stimulation director something I said about him behind his back. I have no reason to think that, my co-resident and I are close enough but not best friends, we are in the same year and smile and joke with each other. Basically I told her not to assign any cases to me that is his. 😂 I mean it’s not the worst thing to say, but I have been having a lot of issues with that attending lately so I just want to avoid them at this point.