[Brian_K_White]

Did you miss their point? They merely used UB, correctly, as a term we all do recognize today.

I will utterly kill all humor by explaining it:

They made a funny observation about a thing that happens. The thing that happens is (today) called UB. The funny observation is that that comment kind of exhibited the outward appearance of what the effects of UB could look like.

It began reciting one metaphore, "enough rope to hang yourself" but mid-way unexpectedly switched to a different metaphore "shoot yourself in the foot", producing a combined invalid nonsensical output. As though a program suffered some UB in the routine for looking up and printing metaphores.

The comment author might have done it on purpose. Maybe they intended to make exactly that joke.

The history of the term UB has no more bearing than the history of any of the other words used.