Nighthawk Diner is a diner in Springfield.
Rex Banner celebrated his birthday there with Eddie and Lou, but he wasn't eating the "Banana Kaboom", some sort of "banana split", explaining that he wasn't happy, showing a newspaper, saying "Beer baron beats Banner." on the head line. While showing them the newspaper, he saw that Barney was drunk when he went against the window. Rex breaks the window and interrogates him, and that's when he found out that Moe's sold beer.