When cutting to commercial he announced the next segment as "The G Block", accidentally using its programming signature. It just stuck.
For years on the Fox web page for The Fox Report there was a link 'Whats The G Block?' or something like that and when you clicked on it, it brought up a picture of an abandoned prison building with "G Block" stenciled on the side. It is no longer there.
Thanks, Island Jeff--didn't know the lingo.