Maureen Dowd, New York Times RICK SANTORUM was locking down the youth vote.The man who fondly recalls nuns rapping his knuckles with rulers did some verbal knuckle-rapping of his own on Thursday with students at a forum in Concord hosted by New England College.Not satisfied with mentioning homosexuality in the same breath as bestiality and pedophilia, as he did in 2003, Santorum tried to win over the kids by equating homosexuality with polygamy.