John Oates -- 'Rich Girl' Was a Dude

John Oates dropped a BOMBSHELL on us in Nashville Thursday night. The Hall and Oates iconic 1977 hit, "Rich Girl" ... is about A GUY!

Oates said the song was written by Daryl Hall ... about a guy who used to date Sara Allen -- Hall's GF at the time. Oates said the dude was a spoiled fast food heir who was a "burn out."

We did some digging ... the guy's name is Victor Walker. His dad owned The Walker Bros. Original Pancake House in Chicago. He also owned 15 KFC franchises.

Oates says Hall was smart enough to know ... "Rich Guy" wouldn't fly.

Song has a whole new meaning ... right?