In biblical terms and times, Moab was a kingdom in what is today Jordan, on the eastern shore of the Dead Sea. The inhabitants or Moabites thrived for roughly a millennia and were antagonists of Israel.
In today’s parlance, M.O.A.B. is an acronym/abbreviation for mother of all bombs and that’s the connotation here, meaning the following will be, for some folks, staggeringly unbelievable, like nukes to their psyches/sense...