In english means: "where do you live?" Used to mark despise for someone lacking the knowledge/information about something very popular, an important event, or someone famous. e.g.:

Person 1: "Did you hear Hayfa Wehbe's latest hit?"
Person 2: "Who's she?"
Person 1: "OMG! you don't know who Hayfa is?"
Person 2: "Nop, no clue!"
Person 1: "Man! wen 3ayesh?"