Cloud Cuckoo Land is a location in The LEGO Movie.
Cloud Cuckoo Land is a hidden realm that rests inside a massive cloud that is located in Middle Zealand and is ruled by Unikitty. To enter it, one must find the rainbow that leads to it and perform the secret knock. This location is where the Master Builders often meet in the dog-shaped building.
According to Unikitty, there are no rules as there is no government, no babysitters, no bedtimes, no frowny faces, no bushy moustaches, no negativity of any kind, and especially no consistencies.
The LEGO Movie
After traversing through Middle Zealand, Emmet, Wyldstyle, Batman, and Vitruvius arrive at the massive cloud where Vitruvius does the secret knock to get them into Cloud Cuckoo Land where they meet Unikitty.
At the Master Builder meeting in the dog-shaped building, the Master Builders are pleased that Emmet has the Piece of Resistance needed to disable the Kragle. Upon finding out about Emmet not being a Master Builder while also hearing about MetalBeard's earlier invasion of the Octan Tower, the Master Builders were uninterested in taking action enough for MetalBeard and Abraham Lincoln to take their leave. Due to a tracker that was secretly placed on Emmet's leg by Bad Cop during the fight in The Old West, the Super Secret Police raid the location where they take every Master Builder present prisoner. Emmet, Wyldstyle, Batman, Vitruvius, Unikitty, and Benny were able to escape in a makeshift submarine.
Due to the damages of the attack, Cloud Cuckoo Land crashes into the ocean and starts sinking beneath it's surface.