Before the introduction of EVMs in 1998, voters wanting to exercise the option of non-voting in secrecy would simply put a blank ballot paper in the ballot box. Some deliberately spoiled the ballot by stamping it at more than one place to make it invalid. Interestingly, many just wrote sab chor hain (they are all thieves) on the ballot. All these amounted to invalid votes. They were counted but did not impact the result.
