Former Vice President Joe Biden told a South Carolina campaign rally crowd on Saturday night that he had a lot of names he could call the president, but he would start with “clown.” Biden, on a two-day swing through the state, then mistakenly referred to Margaret Thatcher as the U.K. prime minister as he tried to boast about his knowledge of foreign leaders. Thatcher led the U.K from 1979 to 1990. “One I can say is Margaret Thatcher, um, excuse me, Margaret Thatcher—Freudian slip,” Biden said, according to Politico. “But I knew her too. The prime minister of Great Britain, Theresa May.” Going back to Trump, who refers to Biden as ‘Sleepy Joe,’ he said he would not stoop to the level of the president’s name calling. “On every single issue and on every demeaning thing he says about other people, I have no problem responding directly,” Biden said. “What I’m not going to do is get into what he wants me to do. He wants this to be a mud wrestling match.”