The Orangeverse is made out of materials that are only orange.
It is impossible for anything in the Orangeverse to be anything other than orange.
For Orangeversians, trying to imagine a color other than orange is like third dimensional being trying to image the fourth dimension.
On the inside, the verse looks like an orange geode.
If an orangeversian gets out of an orangeverse and is in another verse, anything that is not orange will, to them, be seen as orange. This means they can only ever see orange.
If you try to paint the orangeverse with a paint that has an existence rank of 0 and the orangeverse has a higher existence rank, the paint will turn orange.