Explanation: The French MAS-36 rifle had a unique system for storing the bayonet, wherein the bayonet is simply reversed and inserted beneath the barrel and 'locked' in for storage. Efficient use of space!
However, a handful of goofing-off French infantrymen found out that the same system could be used to 'lock' two rifles together, and that doing so blocked the release button... making both rifles unusable without being disassembled.
Great work, GI Pierre! We salute your ingenuity in breaking guns designed to be impossible for any ordinary moron to break! o7