Being under the influence of both cannabis (not necessarily chronic) and ethanol. The letter D in drunk is replaced with C from the term Cannabis (more commonly known as marijuana in the USA).
The origin of the word crunk comes from the O.G. MC ICE-T. It was during an interview with Oprah Winfrey that Ice stated that the word crunk is used in place of ANY curse word. It was during his battle with the PMRC and explicit lyrics hater Tipper Gore. Crunk was used as a curse that isn't censored.