Something old and tired that has been dressed up with a superficial improvement to make it look like it's something newer and better than it is.
Derives from "The Simpsons" episode in which a new women's role model doll designed by Lisa Simpson was ignored by a throng of girl shoppers in favor of a Malibu Stacy doll featuring "New Hat!"
The iPhone 5s is nothing but the iPhone 5 with a new hat.