Why would you hand blank ballot at. That point? You might as well vote.
"I don't like any of the rat-bastards." "I don't care." "I think it's funnier to draw a dick. (And I don't care.)" "I trust other people to make the right choice." "I refuse to participate in this bourgeois sham election." ...are all reasons I've heard, even if I don't actually understand any of them.