lucky dip

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A game in which prizes are covered up and mixed together in a container, so that contestants can dip their hand into the container and randomly pull out a prize.
• noun by extension, idiomatic, figuratively A selection solely at random.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a game in which prizes (e.g., candies or coins) are concealed in a container and for a small sum a player can draw one out at random
• noun a selection or decision purely at random