On Jan. 24, Jennifer Aniston [1] took over as host of The Ellen DeGeneres Show [2] and had some fun in her new role. After revealing why Ellen DeGeneres [3] was unable to make it, the 50-year-old actress introduced a segment in which she visited some Friends [4] fanatics who stopped by the original set of the show [5] at the Warner Brothers lot in Burbank, CA. Loyal viewers got to sit on the famous orange Central Perk couch from the series and snap a photo. Little did they know that the Rachel Green was hiding behind them. Right before the photos were taken, Aniston popped up to say hello, and you better believe there were a lot of excited shrieks. "I know, it's the cruelest thing in the world," Aniston joked after scaring a couple of fans. Watch her shock some of the biggest Friends devotees in the clip above!