Johnny Carson…I did not know that !
Never had heard called that way.
Yes the F4C was initially the F110 (USAF designator), Robert McNamara during the Kennedy admin re-vamped several Strategic, DOD and Global Defense programs and their missions and organizational structures. . .
This link can explain it better 1962 United States Tri-Service aircraft designation system - Wikipedia
If intrested look into the Combat Arms Regimental System or CARS, this was a DOD restructuring of US Army combat forces prior to US involement in SE Asia. U.S. Army Combat Arms Regimental System - Wikipedia