The hairstyle has been around for awhile, but the term “mullet” is comparatively much more recent than the cut. I only heard it maybe three years ago. I don’t have a cite for this, but I read somewhere, I think in the style section of the Houston Chronicle, that the term can be traced to a Beastie Boys song. I can certainly believe that they were ahead of the curve in hairstyle slang, but I am witholding my belief that this origin is accurate.
I did a SDMB search (titles only) to see if it had been asked before. I read some comments about a movie, “American Mullet,” which may have some clues.
Anyone know the Straight Dope on the term “mullet?”