chain of self-service grocery stores, started 1916 in Memphis. According to founder's reminiscence from 1921 arbitrary coinage, simply "something different from anything used before" ["Current Opinion"].
Examples from the Web for piggly-wiggly
Contemporary Examples of piggly-wiggly
If protocol demands that John Edwards look like a banker, his daughter dresses as though she could be going to a Piggly-Wiggly.Cate Edwards’s Courtroom Style Strategy
May 2, 2012