Source : Free On-Line Dictionary of Computing

lace card
     
        (Obsolete) A {punched card} with all holes punched (also
        called a "whoopee card" or "ventilator card").  Card readers
        tended to jam when they got to one of these, as the resulting
        card had too little structural strength to avoid buckling
        inside the mechanism.  Card punches could also jam trying to
        produce these things owing to power-supply problems.  When
        some practical joker fed a lace card through the reader, you
        needed to clear the jam with a "card knife" - which you used
        on the joker first.
     
        [{Jargon File}]