From Fark.com:
I was checking luggage with a firearm in it through Logan one time, and a guy came back to the "special persons" counter (he had been in line in front of me) with a couple of mags for his pistol. He had forgotten to take them out of his pocket (and his suitcase with the pistol in it was already on the way to the tarmac).
Everyone started getting all excited, because a couple state cops overheard this and started demanding to see everyone's firearms cards, yada yada yada.
Then the guy had a brilliant idea. He asked if it was OK to carry an empty magazine on a plane, heard yes, stripped the ammo out of the mags, stuck them back in his pocket, started to toss the cartridges into a wastebasket. The cops started giving him shiat about that, so he said, "well, I'm certain you'll know how to dispose of them properly, officer," stuck the handful of cartridges into the cop's hand, and walked off. Last I saw, the cops were still standing there trying to figure out what to do with two dozen rounds of 9mm.