"Dawg" in American English is slang for "buddy". It does not mean dog, the animal. As Matt pointed out, this is how some younger guys address each other. His example "Hey dawg, are we going out tonight?" could be reworded as "Hey, bud / buddy. Are we going out tonight or what?" in more standard English. Another example is "Hey, dawg. Wassup?" which is slang for "Hey, buddy. What's up?"

Dawg, when spelled that way, is a way that young men address each other. It is very colloquial. "Hey dawg, are we going out tonight or what?"

Dang! = Darn it. Dawg! means dog

Keep in mind that it's only used in dialects that don't differentiate between "o" and "aw" sounds, thus the spelling.

I see! Thank you all! =)