For me, it comes from Phoebes Birthday dinner, when Ross and Rachel are locked out of the apartment and Emma is left inside alone, and Rachel begins to spiral in anxiety and Ross responds with
"Oh my god, you know what, yeah, I think you're right. I think... listen, listen... A pigeon, a pigeon. No, no wait, no, no, an eagle flew in. Landed on the stove and caught FIRE! The baby, seeing this, jumps across the apartment to the mighty bird's aid. The eagle, however, misconstrues it as an act of aggression and grabs the baby in its talons. Meanwhile the faucet fills the apartment with WATER. Baby and bird still ablaze are locked in a death grip, swirling around in the whirlpool that fills the apartment!"
It's just great, so hilarious.