To Libby (verb): to out someone's undercover role, as Lewis "Scooter" Libby (and others) did to CIA agent Valerie Plame.
Her: Yes, I'm sort of a secret agent.
Him: Well, if you keep telling people it's not much of a secret is it?
Her: Oh, you're right! I need to work on my stealth. Sorry.
Him: Don't apologize to me - I'm not the one who Libbyed you.