Used in a situation to express displeasure, annoyance, angst, being "fed up", but said situation not warranting as extreme a response as god dammit. Originated in the southeastern U.S. around the late 90's. Also known as the close relative to the phrase dad gum.
DAD JIMMIT! If my computer crashes one more time I'm going to go postal on its ass.
Cubicle nerd: The dad jim Coke machine just ate my dad jim money!
Fellow cubicle nerd: bummer