pay back
     v 1: act or give recompensation in recognition of someone's
          behavior or actions [syn: {reward}, {repay}]
     2: take vengeance on or get even; "We'll get them!"; "That'll
        fix him good!"; "This time I got him" [syn: {pay off}, {get},
         {fix}]
Source: WordNet® 2.0