On Jan. 24, Jennifer Aniston took over as host of The Ellen DeGeneres Show and had some fun in her new role. After revealing why Ellen DeGeneres was unable to make it, the 50-year-old actress introduced a segment in which she visited some Friends fanatics who stopped by the original set of the show 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!