The worlds funniest joke

The world’s funniest joke. The joke deals with a man getting shot. And when I think about it, I can’t phrase is better than Asimov did in Jokester.

“The point is,” said Meyerhof, “that I have pictured a husband being humiliated by his wife; a marriage that is such a failure that the wife is convinced that her husband lacks any virtue. Yet you laugh at that. If you were the husband, would you find it funny?”.

He waited a moment in thought, then said, “Try this one, Trask: Abner was seated at his wife’s sickbed, weeping uncontrollably, when his wife, mustering the dregs of her strength, drew herself up to one elbow.’

” ‘Abner,’ she whispered, ‘Abner, I cannot go to my Maker without confessing my misdeed.’

” ‘Not now,’ muttered the stricken husband. ‘Not now, my dear. Lie back and rest.’

” ‘I cannot,’ she cried. ‘I must tell, or my soul will never know peace. I have been unfaithful to you, Abner. In this very house, not one month ago’

” ‘Hush, dear,’ soothed Abner. ‘I know all about it. Why else have I poisoned you?’ “

Trask tried desperately to maintain equanimity but did not entirely succeed. He suppressed a chuckle imperfectly.

Meyerhof said, “So that’s funny, too. Adultery. Murder. All funny.”

And these are the “clean” jokes. Why is humour funny?