The Double Rainbow song is widely regarded on Route 50 as one of the most amazing wonders in all the internet. It is the auto-tuned version of a popular Youtube video, in which a man broke down into tears of joy at the sight of a double rainbow at Yosemite. It has been considered by some to be the anti-thesis of "Can you feel the sunshine", a song commonly associated with the Tails Doll, and thus the Double Rainbow song is considered as a song of "light" to counteract the Tails' Doll's darkness. The song's popularity is such that some have joked that to for an isolated member to sing the double rainbow song will automatically allow him or her to be a part of the community. It can be found here: http://www.youtube.com/watch?v=MX0D4oZwCsA
As the song's popularity began to grow within Route 50, eventually the 'double rainbow' itself and even single rainbows have come to be considered divine signs which foretell of good times to come. This is characterized especially in the roleplay "Quest for Pope", where the double rainbow at the beginning of the roleplay hints that the adventurers will succeed in their quest. They are accompanied by Golden Chatots (the species, not the statue), and are the sacred emblem of the Furret Alliance.