There's some dispute over the meaning of "crunk". Some suggest it simply means "very intoxicated" (an intensified form of "drunk"), I prefer the more general, positive definition that is trickier to define.

Essentially, like the cool-groovy-bad-dope-phat continuum, it means "really good", but it has a more specialized usage. An analogy might be that to say a club/bar/party is "getting crunk" means that the "joint is jumping" in an earlier parlance. It means that that intangible matrix of people/music/libation has reached its peak and everyone can really start to enjoy themselves. I'm familiar with the term mostly through hip-hop and rap music, as the establishments I find myself in these days tend to be not so much "crunk" as "toddler-friendly".