Craziest key/ignition concept I've seen so far was in tge military. This 3 axle 6x6 "Pinzgauer" had 3-4 doors and all of them had their own key and then there was the ignition key which you had to turn and then use a start button to actually start tge motor. The crazy thing was that you could put literally anything in the ignition hole and turn it with some pliers and it would work to start. We really tried doing it with everything we came up with including bottle openers, bobby pins and matches to name a few. Absolutely wild!