Ajudge sentences a prisoner to death. the prisoner knows the judge is a reasonable man, and vice versa. the judge says that at one day in the upcoming week, the prisoner is to be hanged, but it will be a surprise and he will not know which day until the executioner comes and takes him away.
the prisoner reasons that the execution cant happen on saturday because if it hasnt happened by friday, it will not be a surprise on saturday. he then concludes that (since saturday has been ruled out) the haging cannot happen on a friday either becuase if it hasnt happened by thursday, friday wont be a surprise. he continues this line of reasoning and concludes that the hanging cannot happen
wednesday morning the executioner comes and hangs the prisoner, despite his pleas and shouts of reason, why?
; )

I think it's a paradox, and doesn't have a proper solution.

But we can try like this :

the hanging can't happen on Saturday, because it's the last possible day, and it wouldn't be a surprise

It can't happen on Friday, because it's the last day when it's not the last day, and equally wouldn't be a surprised.

It can happen on Thursday, because it's neither the last possible day nor the last day when the hanging can happen; but it won't in reality because it's last such day, no similar day is after it. so in a way it's special too

Wednesday, however, leaves more than 2 days after itself (just like Thursday), but it's not the last day with this characteristics. On Wednesday morning Wed and Thurs are equally possible. On thurs however only thurs is possible, as Wed has passed already.

( I am not sure about this, but that's how I understand it)