I think it's weird. You're going over to someone's house for a meal, not a big gathering, and you're asked to bring a chicken? It's customary I thought for the guests to bring sides- pre-dinner nibbles, salad, dessert or drinks I would have thought. But the main part of the main course is pretty odd.
yeah, I know but that's typical of these people. It's like their trying to avoid the cost of hosting, but want to appear to be hosting... Ha!