Source : WordNet®

tell on
     v 1: give away information about somebody; "He told on his
          classmate who had cheated on the exam" [syn: {denounce},
           {betray}, {give away}, {rat}, {grass}, {shit}, {shop},
          {snitch}, {stag}]
     2: produce an affect or strain on somebody; "Each step told on
        his tired legs"