From a Moscow Times article about how the world almost blew itself up cold war style:
Consider, for example, a fun Cold War-era fact from Bruce Blair, who is president of the Washington-based Center for Defense Information … Blair was a Minuteman nuclear missile launch officer in the 1970s, and regularly ran through simulations in which he and his colleagues launched up to 50 missiles at the Soviet Union.
To launch a Minuteman in those days, one had to “unlock” the missile by dialing in a code — the equivalent of a safety catch on a handgun. However, Blair reports, the U.S. Strategic Air Command was worried that a bunch of sissy safety features might slow things down. It ordered all locks set to 00000000 — and in launch checklists, reminded all launch officers like Blair to keep the codes there. “So the ‘secret unlock code’ during the height of the nuclear crises of the Cold War,” Blair says, “remained constant at 00000000.”
As much as the cold war did for improving the quality of movie bad guys we got damn lucky some nut didn’t decide to press 0000000 into a keypad somewhere.