I believe the Old Gods are the eldest users of the Phansite. Or prolly something like that. I don't really know my Phansite lore.

It means a dead meme that nobody knows the meaning to beside it's creator.

Someone linked me this so I guess I gotta respond The old gods were a thing that happened when I brought back old posts claiming to resurrect the old gods, as in chaotic beings recognized by the community, the one I tried to bring back was an account called “Naked Mitsuru” (also megaman(1), Yamcha, the ghost zone from Danny phantom, Xehanort, and Sans Undertale are old gods because why not I made the idea of the old gods I decide who they are)