How did I get the "What does it mean?" achievement?

achievements borderlands-2

This sequence is triggered on an overlook with a tent in east of The Highlands. It's most accessible from the cliff at the end of the Hyperion base on the east side of the map. Jump straight down to the tented overlook. Either Handsome Jack or Claptrap will imitate the popular "Double Rainbow" clip and trigger the achievement. A "double rainbow" glows in the distance:

all the way across the sky

Video walkthrough by GameFront:

Related

Are blueprints found on the black market unique?
Base stat differences between classes
Who/what is Saturn (close to the end of the game)
Is it feasible to solo farm the Uber bosses?
How can I change Dwarf Fortress' ASCII color scheme?
How can I stop playing nether portal tag with a mooshroom?
Is there any benefit to pre-purchasing Heart of the Swarm?
What do I do in Technic/Tekkit?
How do I prevent my fingers from hurting when playing fighting games with a gamepad?
Which NPCs can point me to San Francisco?
Should Sheared Sheep Sprout Surplus Stuff?
How should I play Cammy against a patient defensive Guile?