Its a board game, involving 3-8 players, based on the game pictionary. In pictionary, you try to draw a certain word within a time limit, and without speaking, others are trying to guess it. BUT in the case of this game, it involves marijuana, and the time limit is how long you can hold the hit of smoke in your lungs.
Pictionary is derived from the words "picture" and "dictionary"; Hitionary is just a playing on the name of the real, but sober game, and instead of "pic" its "hit".

(noun) A successful type of theft which results in an acceptable, impressive and rewarding payday for the protagonist.