A not so subtle reference to Attorney General William Barr flying all over the world to investigate “Deep State” politics and international connections to it.
Of course it is entirely improbable that Attorney Generals travel all over the world to look into screwball conspiracy theories, but AG Barr has made the improbable come true, so we can now say “when pigs fly” and really mean it!
An expression used to describe a 0% chance of something ever happening. This means that the event is completely impossible, no longer exists, and will never happen.
Example 1:
Person A: "Do you think they'll ever bring back the original Times Square Toys "R" Us with the indoor Ferris wheel?"
Person B: "Yeah, when pigs fly. That space is a Gap now."
Example 2:
Person A: "I'm waiting for the MTA to bring back the V train and paper MetroCards."
Person B: "Keep waiting. That'll happen when pigs fly."