Definition of whup-ass in English:

whup-ass

noun

in phrase open a can of whup-ass
US
informal
  • Deliver a sound beating or overwhelming defeat.

    ‘he stared into the crowd of reporters, ready to open a can of whup-ass’
    ‘we could sneak up on him later and open up a can of whup-ass on him’

Origin

1980s: from whup + ass.