Midwesterner here. Admittedly, some of these can be... interesting (to be interpreted as passive aggressively as possible). Some can be excellent though. We have a pistachio salad in the family that is a go to, and if I don't control myself I could eat a whole batch.
Ingredients include: whipped cream/Cool Whip, pistachio pudding, mini marshmallows, diced pineapple, and of course chopped pistachios. It's obviously more of a dessert/sweet side dish type of thing. Pistachios alone, though delicious, wouldn't fill the same role.
Yes, Captain. The contagion seems to be spreading rapidly. Almost as if people are finding the combination appetizing, and are perpetuating the phenomenon by way of potlucks and recipe sharing.