Both ladies — but the night was anything but ladylike — were guests on the funnyman's show, with Aniston promoting her new film Horrible Bosses 2 and Kudrow promoting her comeback on The Comeback, and Kimmel decided that the former costars should go head-to-head to see who has the dirtiest mouth.
"If you're faint of heart, I'd like to ask you to cover your ears," Kimmel warned viewers.
Each actress was then given five seconds to come up with the most vulgar words that they could, and the rules stated that they could only use a curse word once. The game then continued until one of the women failed to deliver a vulgar (but pretty hilarious) retort.
Kudrow lost the coin toss, which meant that Aniston chose to start, and her word of choice was "dick-licker."
"You're off to a very strong start," the show's host said with a laugh. Kudrow then responded with, "C***sucker."
The competition only gets more intense from here onwards, with some Greek curse words being thrown in here, as well as Kudrow's dirty vocabulary on display thanks to the words she's picked up from her teenage son.
Some choice insults included phrases like "f***ing shit," "holy f***balls," "schmuck," "asswipe," and "undercarriage eater."
The bleeping was definitely necessary on this one.
Watch the hilarious video and see who the winner was.
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