It all started with The Pig.

These days, the Piggly Wiggly is our neighborhood store for grabbing a gallon of milk, a few boxes of cereal, and a loaf of bread, but 100 years ago it was a groundbreaking enterprise that changed the face of grocery shopping. When Piggly Wiggly opened its doors in Memphis, Tennessee on September 6, 1916, it was the first truly modern American supermarket.

Before Clarence Saunders opened his shop, anyone who needed groceries would hand their shopping list over to a clerk who would pluck the groceries off the shelves and hand shoppers a bag full of their items. Piggly Wiggly turned that model on its head. Shoppers were invited into the store, handed a shopping basket, and left to wander the aisles of the grocery store, filling their cart with whatever products caught their eye. It's hard to imagine now, but no one had ever thought of self-service grocery shopping before. According to TIME, who dug into Piggly Wiggly for the store's centennial, Piggly Wiggly was the original grocery store, who not only introduced grocery carts, but also "price-marked items, employees in uniform, and the supermarket franchise model."

Piggly Wiggly permanently changed the face of grocery shopping not only in the South, but around the world, and while its place in history is well-documented, there's one part of its history that no one seems to know about—where exactly it got its whimsical name.

According to the Piggly Wiggly website, the name's origin is truly a mystery. Saunders never fully explained where he got the idea that naming a supermarket after a squirmy porker was a good idea. Instead, he let stories circulate and, like a politician, neither confirmed nor denied them. One story claims that he came up with the name during a train ride where he looked out his window and saw several little pigs struggling to get under a fence. That made him think of the rhyme "piggly wiggly" and that apparently sounded like a good name for a grocery store. Another original story floating around is that when people asked Saunders why he gave his grocery store such a funny little name, he's reported to have said, "So people will ask that very question." It seems to have worked, because here we are over 100 years later asking still asking the question. One thing for sure, though: It's memorable.