You joke, buuuuuuut https://arstechnica.com/tech-policy/2013/12/launch-code-for-us-nukes-was-00000000-for-20-years/
The USAF has denied this, multiple times.
I do not believe them.
Mainly because I know how people were during the cold war and have no doubt in my mind that the thought process was "nobody will ever access this without a reason, so let's make it super quick and easy or we might be radioactive slag before we finish typing"
The mere fact that it's believable is a problem.
Personally I like "Shit tends to clump together."
And "the turd doesn't fall far from the asshole"