The 50-year-old actress serves as the guest host on Friday's episode of The Ellen DeGeneres Showand uses her time on the Warner Bros. lot to pop over to the set of Friends, which was shot in the same place and is currently part of the studio tour.
In the clip, a group of fans enters the Central Perk set and quickly reveals that Ross (David Schwimmer) was their favorite character on the show. As the girls pose for pics on the iconic couch, Aniston, who played Rachel on the series, jumps up and screams, "Ross?! Who said Ross?!"
Aniston surprises the next group by appearing with a pot of coffee and shocks the next duo by screaming "espresso!" as she makes her presence known. When the next guests question if they're dreaming, Aniston replies, "No, you're not dreaming," before quipping, "I live here."
The shocks continue with two girls who, much to Aniston's dismay, pick Joey (Matt LeBlanc) as their favorite Friends character. But when they can't stop screaming once she appears, Aniston assures them, "I love Joey too! We all love Joey!"
The last visitors pick Phoebe (Lisa Kudrow) and Monica (Courteney Cox) as their faves, causing Aniston to joke, "I'll pretend I didn't hear it."
Back in October, ET caught up with Aniston, who gushed over her Friends co-stars.
"It's just like going home. We have the best time together," she said of spending time with her former castmates.
As for the possibility of a reunion with the group -- HBO Max recently announced that they're working on a Friends special -- Aniston admitted, "We are always trying to think of something to do, but we have to figure out what the right thing is. But we will."