It’s a pun on desert/dessert. At first you think they’re in a desert and the character pronounced it wrong/author spelled it wrong, but the final panel reveals that it was accurate and they’re on top of a large dessert, which is possibly also a desert as well

That’s great! Did you make it yourself?

It’s been borrowed into graphic design as the Cicada Principle:

https://lea.verou.me/blog/2020/07/the-cicada-principle-revisited-with-css-variables/

Looks like the original link is dead, but there’s a newer examination of it. If you have a repeating pattern, you can maximize variation while minimizing file size by using multiple sequences with different prime lengths