Friends: 16 Easter Eggs You Totally Missed

16. Mad About Pheebs

Before the character of Phoebe Buffay had ever graced our screens, audiences had already met her rather less pleasant twin sister Ursula. 

The character, played by Lisa Kudrow, was a character on NBC sitcom Mad About You, which started a couple of years before Friends. This is referenced in the episode The One With Two Parts, Part 1, when Helen Hunt and Leila Kenzie make cameo appearances. 

They mistake Phoebe for Ursula, much to the befuddlement of Pheebs, and the reason is that they were playing their own characters from Mad About You, where they would regularly frequent Riff's, the restaurant Ursula works at.