On the 28th of November each year, you will get the chance to remember all the friends that you've met in the past that had no toxic relationships with you, and who spent a long time with you as friends. These friends can be remembered as online friends or IRL friends. They can be remembered in any way you like.
Those friends can also be the people who you used to be close with, but then you stopped talking with them (also vice-versa) and now you barely/don't talk with them. This is a happy and nostalgic day that doesn't have to be celebrated, but it's quite fun if you do. It'll bring back memories.
"Woah! It's Old friends day!"
"What do you do when it's Old friends day?"
"I like to message my old friends I've known for quite a while and say hi because I barely talk with them anymore."
"Oh, like your best friend '(example)'? You always message them every year."
"Yeah, like that."