We've all learned to be wary when you get a phone call or email telling you you've won a competition you don't remember entering - it's nearly always a scam.
However, it is possible to win prizes just for doing your normal shopping, without having to come up with a tie-breaking slogan or even actually enter a competition.
We look at three ways you can take a flutter while you shop.
HSBC is teaming up with Google for a prize draw giving customers the chance to win prizes worth up to £50 - just by using Android Pay. The company has more than £1 million to give away through Tap Moments.
New Android Pay users using an HSBC will automatically be entered into the giveaway each time they tap and pay using their phone - and there's a one in five chance of winning a prize.
These include up to 150,000 Costa Coffee gift cards worth £3; 30,000 PizzaExpress gift cards worth £10 and up to 11,000 House of Fraser gift cards worth £20. There are also up to 13,000 pairs of adult Odeon cinema tickets and 6,000 Currys PC World gift cards each worth £50. The competition's open already and ends on 12 December.
New shopping site Boom25 has a clever twist - it refunds one customer in every 25. It works with retailers selling everything from handbags to holidays, including Boots, New Look, Currys PC World and Expedia.
If you're the lucky 25th person, you'll get your whole spend back, whatever the size - meaning you could even get a holiday for free. There's no limit on how many times you can win, and all you need is a PayPal account to receive your winnings. There's more information here.
Open a Virgin Money Credit Card account, and pick the Manchester United design. Then, for every £1 you spend or transfer, you'll get an entry in a free draw as well as a further automatic 10 entries a month.
Prizes include Manchester United matchday tickets, signed shirts and hospitality tickets - and, twice a year, the bank's Mega Draws offer even bigger prizes. There's more information here.