It's one thing to cite it as prior art, but if they are listing it as an example embodiment of their invention then the patent is invalid.
The idea of filing a patent application as a "joke" is nonsense.
What exactly would it mean to file a patent “as a joke?”
E.g., https://uspto.report/patent/grant/10,282,296
It wouldn't be the first time a patent for something absurd was granted.
