A mean, spiteful old woman that likes to constantly reprimand/torture the younger portion of the human race. Usually associated with witches and strict librarians.
When smoking a spliff (a marijuana/tobacco cigarette), you do not take a "hit" or take a "drag" - you take a "hag" of a spliff. The amount of time to hold in the "hag" is proportional to the marijuana to tobacco ratio. The larger the amount of weed, the longer the "hag" is held in.