Tattling on someone for coming in late to work is not a good thing to do and so being happy about it would be considered sarcastic.
Context: "I couldn't believe that my coworker told my boss that I came in to work 15 minutes late this morning. " Claim: "I was completely proud when my coworker tattled to my boss that I came in 15 minutes late this morning"
Considering the context, is the claim true, false, or unknown?