The term "Herbert" was an uncomplimentary slang term used by the acolytes of Dr. Sevrin. The basis for the term was a minor official named Herbert, notorious for his rigid and limited patterns of thought.
In 2269, Sevrin's group referred to Captain Kirk by this moniker several times, and Spock once (who denied the comparison), as the officers were interfering with their attempt to locate Eden. Unfamiliar with the term, Kirk asked Spock what it meant, and Spock told him, prompting Kirk to reply that he'd try to be less like the individual described. When blocking the halls of the USS Enterprise, they protested by shouting the phrase over and over. (TOS: "The Way to Eden")