Underground meaning that these snack cakes, cookies or little debbies (new to the public or rare in certain areas) have been bootlegged from a different state or shipped to a state that's not currently selling them to the public.
Hey Charlie, where did you get that KitKat Candy Bar?
Charlie: Oh I ordered these off the internet.
Dang, those are some of them underground candy bars there~!
Charlie: Oh I ordered these off the internet.
Dang, those are some of them underground candy bars there~!
by Sawedoffsob June 8, 2016