Originally used in greeting those who names are unknown to you or have been forgotten, dun has been revolutionized to act as a comma or pause in a sentence, indicating also that the following part is of significance and those around should stop what they are doing if possible and pay close attention. However "DUN" is also used when speaking with close friends and can take on several positions of a sentence.
"Ayo where ya going dun"
"Ayo dun, we bout to go down the road and handle buisnes"
"wassup dun" "safe dun"