Jennifer Aniston has once again been betrayed -- this time by her former Friends costars! In a hilarious new skit taped for Wednesday's episode of Ellen (which Aniston is co-hosting), the 43-year-old actress pays an early morning visit to the L.A. home of Matthew Perry. Seeking Perry's advice on co-hosting, Aniston instantly annoys Perry, who suggests she call next time.

"We used to walk into each other's apartments all the time," Aniston argues. "I mean, we're friends!"

Snipes Perry: "That was a TV show, we haven't actually seen each other in a pretty long time, like eight years."

Cluelessly calling Perry "David," Aniston insists that's "not true" -- just as Courteney Cox appears at the front door, obviously attempting a walk-of-shame exit after a night at Perry's.

"Lisa?!" Aniston's real-life BFF asks.

"It's Jennifer!" she protests.

"You're not sleeping with her too, right?" Cox asks Perry.

"No, of course not," he insists."You're still dating that writer guy [Justin Theroux], right?"

"You are disgusting!" Cox tells him. "I'm never sleeping with you again!"

Watch Aniston's tearful reaction -- and further shock when two more very famous women sneak out!