The offspring of "Dam" and "Fuck", and also a short form for Dacoit - a thug from India. The great thing about this word is that you can say it in front of your parents or little kids, cuz what do they know? It's just "Dack". Yet it provides the phonetic and guttural satisfaction of using the F-bomb or saying Dam - two longstanding pillars of profanity.
You're a dack - that's all I gotta say.
What the dack are doing?