When I was a kid, it’d have to be Memorial Day. All the extended family would convene at the old family cemetery to decorate the graves. That isn’t the weird thing… the weird thing was we treated it as a family reunion and picnicked together among the head stones.
My sister did this with her ex-inlaws except it was Pinochle which they taught to me as a teenager when I was there on an extended visit. It was also pretty damned fun.