Article continues below advertisementDonald Trump had his attention on more than just politics during the swearing-in ceremony for Homeland Security Secretary Markwayne Mullin.On Tuesday, March 24, Trump cracked a joke about Mullin's wife, Christie Mullin, 47, saying she looked far younger than her age during the White House event.Article continues below advertisementSource: MEGADonald Trump joked about Christie Mullin at a White House event.