nostalgia day 

december 5th is the day

They: hey! It's december 5th, it's nostalgia day!
He: ah yes, time to put my old avatar on

nostalgia day by markusistaken December 2, 2021

the nostalgia day

a day when everyone sets their avatars and names in social networking apps/sites, example: discord

They: hey! It's the nostalgia day!
He: ah yes, time to put my old avatar on

the nostalgia day by logixcool March 10, 2021

nostalgiadamus 

noun. a.k.a., The Man Who Saw Yesterday. Someone who is hung up on the past and can only talk about "the good old days". A cultural dinosaur. Drives a K-car and wishes for a DeLorean. Thinks Bananarama will have a comeback. Old school, but even more so.

Dude, she is so retro, I'm talking like, nostalgiadamus retro.

nostalgiadamus by Nostalgiadamus, himself July 6, 2006