Unlike the first presidential debate, Mitt Romney's controversial "47 percent" comment came up during the first half of Thursday's vice presidential debate. Vice President Biden was the first to bring it up, but Republican vice presdiential nominee Paul Ryan (Wis.) appeared to come prepared with a rebuttal of his own. 

"I think the vice president very well knows, that sometimes the words don't come out of your mouth the right way," Ryan said. 

The reference is to Biden's knack for gaffes.