Yankees manager Aaron Boone absolutely lost it on an umpire during New York's game Monday night ... becoming so enraged, he actually mocked the guy in front of the entire stadium at home plate.
The wild scene all happened in the eighth inning ... as the Pinstripes were down 2-1 to the visiting Chicago White Sox.
Laz Diaz -- who's zone had been questioned by Yankees players and coaches throughout the evening -- called Anthony Volpe out on strikes ... and that's when Boone blew a gasket.