"Yes, thanks, man."
Native english speaker, but I'm in my 5th year studying German, and hear about this and decided to check it out. I believe that the proper phrase would be along the lines of, "Mensch, danke!" i have never heard "Mann" being used in this context. My German professor is a native German speaker, I might have to ask her.
I'm native German and agree that you can say this. However, it is a newer and very informal expression and usually it's (young) men saying that among each other. Probably you wouldn't necessarily say "Ja, danke, Mann!" but rather "Danke, Mann!" [or even "Ey, danke, Mann!"]
Like I said, it's informal and you wouldn't say that to a stranger or your teacher. :-)