This is either the best, or the worst, lateral thinking puzzle ever (depending on your point of view).  First, here is the question:

Two men went into a restaurant. They both ordered the same dish from the
menu. After they tasted it, one of the men went outside the restaurant
and shot himself. Why?

Thoughts? Ideas? Wild guesses? Honestly no amount of thinking will bring you close to the real answer given which, I promise you, is astonishing and utterly flabberghasting. It might as well be ‘the man realised he was going to be part of a lateral thinking problem and killed himself in a brave attempt to stop people’s suffering before it began’. Based on the information there, it works just as well the real answer, which is below:

The dish that the two men ordered was albatross. They had been stranded
many years earlier on a desert island. When the man tasted albatross he
realized that he had never tasted it before. This meant that the meat he
had been given on the island was not albatross as he had been told. He
correctly deduced that he had eaten the flesh of his son who had died
when they first reached the island.

What?! There’s no way you could deduce, induce, or otherwise detect all of that that from the little information in the question.  The only way to arrive at that is after several hours of frustrated and increasingly wild guessing.

That’s it.

I’m done.

I’m sticking to logic from now on.