WRBL Columbus, Georgia began as a radio station in 1928 and eventually a TV station. RBL (for most) has always stood for rebel, as in Confederate rebel. I always thought RBL had been requested by the first owner (which would also be making a statement) but the FCC actually assigned it randomly. WRBL came up with rebel marketing on their own. Although, there is another, lesser held "theory" that WRBL stands for Wireless Radio's Bill Lewis. The TV station used a "little boy rebel" in their marketing for years. I'm not sure if the radio station started the rebel imaging though.
https://en.wikipedia.org/wiki/WRCG
https://en.wikipedia.org/wiki/WRCG