lucky dip 
noun British
1A game in which small prizes are concealed in a container and chosen at random by participants.Early Learning Centres around the UK, including the store in the Brunel Plaza, are offering a host of activities including colouring, sports tournaments, face painting, lucky dips and games to make the fundraising effort fun....
- Santa will be there on the day with his huge sack of toys for boys and girls, who will also have plenty to occupy them with lots of games, lucky dips, etc.
- So, they will have lucky dips and grand prizes - stuff which pleases the customer and makes them spend that moolah.
1.1A process of choosing or deciding something purely at random: [as modifier]: beware of lucky-dip deals which specify only the type or rating of accommodation...
- Until last year, everyone at York paid the same for their rooms wherever they were in a lucky-dip system.
- Because there were so many servings to prepare in a short amount of time diners received their meals in a lucky-dip fashion from the six waiting students and head waiter.
- take something on
- take something on board
- take something out
- take something out on
- take something over
- take something personally
- take something to heart
- take something to the next level
- take something under advisement
- take something up
- take something with a pinch (or grain) of salt
- take stock
- take that!
- take the air
- take the biscuit (or take the cake)
- take the bread out of (or from) people's mouths
- take the bull by the horns
- take the cake
- take the chair
- take the chequered flag
- take the chill off
- take the count
- take the easy way out
- take the edge off
- take the fall