Australians have to vote, it's the law. You can put a line through the ballot paper if you don't want to vote for anyone. But you do have to turn up and get your ballot and drop it in the box, even if it's blank, or has a penis drawn on it.
Incorrectly filled out ballots obviously don't count, but they are tallied and the total numbers published along with the votes.
Anyone that's ever participated in the vote count will have stories to tell of some of them. People can get very creative with a pencil and can turn the ballot into some fine artwork.