Here's a breakdown of the phrase:
* You: The person being addressed
* Dash: To run, to evade, to give the slip
* Mi: Me
* Weh: Where
So, the literal translation is "You have run me where". It implies that someone has been avoiding or delaying giving you something or information.
Example:
* "Mi ask him fi di money las week an him still dash mi weh. " (I asked him for the money last week and he's still been evasive.)