Acting very low-class, ill-mannered, foul-mouthed, and racist; acting like trailer trash
Ever since Sue married Bubba, she's become just as crackery as he is!
Used often. . . by me, anyway. . . as an espression of great joy, great exasperation, as a substitute for cursing. . . pretty much an all-purpose term of strong emotion.
Usually a one-word exclamation.