Originated in Springfield, Virginia. A way to say hello, or can also be said when extremely happy. You can also use this term when you feel the need to be completely random, or when you want to tell someone to chill out.
A: "What's good, sahn?"
A: "You made the shot!"
A: "Hello class, today we will be learning abou-"
A: "Man, I'm so blown! :"
B: "Haagendaz yo. Haagendaz."