Well, actually it should be: "Was meinst du?" translated: "What do you mean?"
And by the way it's rude spoken/written German.
Alter, ich bin kein Ausländer, (also) was meinst du means: "Dude, I'm not a foreigner, so what do you mean?"
But that's it!
Viel Glück!/ Good luck!
EDIT: I was thinking about your question and I would also say that "meinst du was" could mean: Do you mean something special? But together with "Alter, ich bin kein Ausländer" in front of the phrase it sounds pretty strange to me to be honest.
I am Austrian