And to add further to the joke here the full saying goes more like

>There are only two hard things in Computer Science: cache invalidation, naming things, and off-by-one errors.

And, if you actually work in software a very large portion of your hard to troubleshoot/fix issues are going to be the above.

It's not to be taken as a serious assessment of actual "hardest problems", but they're all difficult. Naming things is obviously impossible. Everyone gets cache invalidation wrong at first, from Intel/AMD to your build system.

> Try to say that at job interview if you don't believe

If your interviewer doesn't at least crack a smile when you make the off-by-one joke, run, do not walk, to the nearest exit. You don't want to work with that dude

Well, there's the variation I heard recently:

There are only two problems in computer science. We only have one joke, and it's not very funny.

Naming things is one of the hardest problems we have. In general. Taxonomy is incredibly difficult because it is essentially classification.

And things never fit neatly into boxes. Giving us such bangers as: Tomatoes are fruit; Everything is a fish or nothing is a fish; and Trees aren't real.

To spell it out for you...

1. It's a joke. The hyperbole is intentional, but it does communicate something relatable.

2. You don't need a citation. Probably anyone with enough software development experience understands the substance of the claim and understands that it is (1).

In case you need to hear this again,

> “Sarcasm is difficult to grasp on the internet, but some people apparently have more visceral reactions to their misunderstanding than others.”

Yes, and we also need a citation about that quote about a horse and a duck walking into a bar. It doesn't sound very likely to me.

Martin Fowler has some history of this joke: https://martinfowler.com/bliki/TwoHardThings.html