Playing off the severe winter weather, Jimmy Fallon on Monday aimed a few “It’s so cold ...” jokes at the Trumps before a surprise guest butted in to continue the monologue. “It is so cold, I watched the ‘Melania’ movie just to warm my heart,” the “Tonight Show” host cracked. “It’s so cold, President Trump got a space heater installed in his MRI machine.” New York City Mayor Zohran Mamdani then stepped onstage. “Hey, Jimmy, let me try one,” he said to wild applause. “It’s so cold in New York City the rent froze itself,” Mamdani said. The city leader...