Obama joined Fallon and comedian Will Ferrell -- who were dressed as teen-age girls Sara and Stacy -- for "Ew!," one of the most popular sketches from Fallon's previous "Late Night" program, NBC said.
During the segment, the "girls" chatted in a family room about things that gross them out. Famous for her health initiatives, Obama said "Ew!" to jelly doughnuts and offered Sara and Stacy kale chips instead. She also exclaimed, "Ew!" when shown a photo of Ferrell dressed as himself, NBC said.