>>63903298The Russian MoD was touting that their cage armor can stop top-attack munitions like Javelin, there were even published articles. This is where the expression came from. It's not the bar armor principle on itself that was called a cope cage, but the hastily welded pieces of metal meant to stop a fuck-you tandem warhead.
Found this old pic that I had saved, links should probably work, there is an archive link there.
Don't get me started on the Cope Bucket modification that was meant to work as a heat seeker decoy which turned out to help the seeker find the vehicle at higher sensor temperatures.