The act of consistently covering for your boss, friend, or other person, by dodging questions, making excuses, changing the topic, or even exaggerating or lying. The slang term originates from the actions and behaviors of White House Press Secretary Jay Carney for the Obama administration when asked questions on certain topics by reporters.
Person 1: What's the latest on that debacle? What did Mike say?
Person 2: I don't know, Mike pulled a Jay Carney and said it happened a long time ago, as if a few months was a long time ago and now it somehow doesn't matter.