Giant Eagle is a chain of grocery stores very popular in and around Pittsburgh, Pennsylvania (and possibly elsewhere).
Its popularity stems from the great selection of groceries at relatively low price. Its popularity in Pittsburgh is expressed by the way Pittsburgers refer to it, they simply call it Iggle, as is even mentioned in a book on how to talk like a Pittsburger.
I sure wish we had one where I live now, as the prices of groceries in my current town of residence are on the average 50% higher than I was used to when shopping at Giant Eagle.