In "The One With Phoebe's Cookies" (Season 7: Episode 3), Monica asks Phoebe if she can have her grandmother's famous chocolate chip cookie recipe as an engagement present to her and Chandler.
But Phoebe realizes her copy of the recipe got destroyed when there was a fire in her apartment.
While they struggle to remember what the recipe said, Ross suggests Phoebe get in touch with her estranged twin sister, Ursula.
And this is when we learn about her apparent date of death.
IDK if you've noticed, but today happens to be October 15.
So, in exactly 17 years from today, Phoebe will live her last day on Earth. According to her, at least.
Friends was notoriously bad at keeping track of everyone's ages — there was little consistency with characters' birthdays and ages, so it's impossible to know how old Phoebe *actually* will be in 2032.
But if we follow the timeline based on when her 30th birthday was — which was actually her 31st birthday as we found out thanks to Ursula — Phoebe will probably be 62 years old (or close to it).
Ross tried to make light of Phobe's comments and mock her ~craziness.~
But he should've known better.
Lol c'mon Ross.
Sidenote: As it turns out, Phoebe's grandma's recipe was actually just Nestle Tollhouse's recipe for chocolate chip cookies.