Mahane Yehuda is also known as The Shuk, because it's the largest shuk (market) in Jerusalem. It takes up a whole small neighborhood, between Yafo and Aggripas, and is at the heart of a much larger shopping complex which stretches up Yafo towards the Old City or up Aggripas, over King George and into the Ben Yehuda triangle.  Mahane Yehuda (pronounced Machne) is as much a place to be as a place to shop. Prices are marked with chalk on blackboards stuck in amongst the produce, and what sells for 6 shekels a kilo on Monday morning may be down to 2 shekels before the trumpet sounds Friday afternoon for Shabbat. The traditional merchants in Mahane Yehuda yell out their prices and other enticements, like "You can't believe it" or "Only a friar (sucker) wouldn't buy." The frenetic atmosphere probably leads to a lot of tourists buying stuff they don't have a clue how or where to cook, just for the fun of it. 

From: http://www.fonerbooks.com/guide_30.htm