Buddy of mine was in an artillary unit in WWII. By the time the party was over, he had a couple battlefield pick-up M1 Carbines, Garands, and .45's he was looking to bring home. When they got pulled off the line, they got a big speech from a sergeant about how they'd be spending time in prison for any bringbacks, he really put the fear of God into them and caused a lot of them, including my buddy, to put their stuff in the amnesty barrel.
They got the same speech when they got back to Britain, and then again in New Jersey when they got home. After those speeches, though, they were also told that there was going to be an "inspection", and if they had any souveniers they should get them out of sight. The inspection consisted of an officer walking down the middle of the barracks tent, looking straight ahead. If he and his friends hadn't fallen for the initial fear-of-God speech on the line, they could've brought all their toys home.