what is a hanging chad or what does it mean?

The hanging chad (and pregnant chads) were infamous in the 2000 election down in Florida. Florida voting ballets used a punch paper system, and chads were the names of the square little bits of paper that were supposed to be punched completely out of the ballot. Due to human and machine variables not all chads were completely freed from the ballot slips, and these were called “hanging chads”. (Pregnant chads were not cut from the ballet at all, but were a bulge in the paper where someone only partially pressed the lever that was to remove the chads.)

Hope this helps. :)