A Jewhole is a loophole that Jewish people employ, so they do not perform an "act of work" on the Sabbath or Shabbat, which is the Jewish day of rest.
Orthodox Jewish Wife: It's almost Midnight, we cannot put our groceries in the fridge, it's already the Sabbath.
(Opening a fridge often switches on the light inside, and switching on a light is considered an act of work that is prohibited by Jewish Law.)
Orthodox Jewish Husband: That's why we have Jewholes.
Orthodox Jewish Wife: What do you mean?
Orthodox Jewish Husband: I will just ask our Christian neighbour to come over and open our fridge for us.