Edit: Thanks for your kind comments on disabling contributions. I'm aware of the possibility, this is just a meme.
Contributions in open source projects are great, needed and make the world a better place after all. Therefore they should be declined politely, optionally by giving a reason.
I hereby inform you that I will no longer accept contributions to this post /s.
This is not what the meme implies. This is rejecting all PR, regardless of quality or fit. That, I don't get.
It's an exaggeration for the purposes of humor. Its not that deep.