Michelle Obama is headed back to Jay Leno’s stage. NBC announced Monday that the first lady will make her third appearance on “The Tonight Show” on Aug. 13 to talk about the London Olympics and life with President Barack Obama and their children at the White House. On her last stopover in January, the first lady promoted her “Let’s Move!” campaign to get kids excited about fitness and healthy eating habits. She managed to convince vegetable-hating Leno to nibble on apples, sweet potato fries and a pizza made with eggplant, green peppers and zucchini. In London, she played a little tennis with kids, handed out some hugs and posed for photos with strapping athletes as she formally began her stint leading the U.S. Olympics delegation. … Nickelodeon’s hit show “iCarly” made Jennette McCurdy a star, and although the show will air its series finale in November, the 20-year-old doesn’t have to worry about what comes next. The network has tapped McCurdy and actress Ariana Grande to star in a spinoff tentatively titled, “Sam & Cat.” The series will follow the girls’ characters, Sam Puckett from “iCarly” and Cat Valentine from “Victorious,” as they become roommates and start a baby-sitting business. “Sam & Cat” will be produced by Dan Schneider, who is behind Nickelodeon shows “iCarly,” ”Victorious,” ”Zoey 101″ and “Drake & Josh.” “I couldn’t be under a better person’s wing, so I’m really happy about that decision,” McCurdy said in a recent interview. “I haven’t seen a script … so I’m dying for information.” McCurdy describes taping the series finale of “iCarly” as emotional. McCurdy hopes that celebrities will appear on the new show, as they did on “iCarly,” which included guest spots by first lady Michelle Obama, One Direction and Jane Lynch. Who would be her ideal guest star? “Andrew Garfield. I’m gonna marry him,” she said with a laugh.