It's not a new one, but I thought I'd advise people in case they are ever in the same situation.
I was in Southern Spain a couple of years ago with my partner. We walked past a couple on the street who looked well dressed and respectable, speaking fluent English. They were handing out free scratchcards for some locally run lottery, as some kind of promotion allegedly. They were fairly nondescript aesthetically, and you didn't actually see what you could win, just generic 'Big prizes!!' kind of text. My partner accepted four from their bundle of cards and started scratching them as we kept walking.
Lo and behold...... we had a winning scratchcard. She got very excited and wanted to go straight back to the couple to see what she had won. But as I'm a cynic at heart, I thought it was too good to be true that we were randomly handed a winning scratchcard in the street. What I was more curious about was that the scratchcards all looked totally identical, so when they pulled some from their bundle to give us, how did they know it was one of the 'winning' ones?
By this stage the couple had walked towards us and engaged with my partner, while I was standing off to the side with the scratchcards, studying them. They were acting almost as excited as she was and seemed keen to get us to go with them back to their HQ so we could sort out the paperwork and our prize. But I stubbornly ignored them as they were talking to me and kept looking at the cards. Finally I spotted it - each scratchcard had a barcode on the rear with an identical number above it in tiny font, apart from the winning one, which had one variation in the number that wasn't easy to spot. I think it was a 7 instead of a 1. So it was a dud that they were able to select specifically from their bundle.
I tore it up while calling them a few choice names, then told my partner we were leaving. She was fairly upset (at me!) initially until I explained it. I contacted the Spanish police about it, but they couldn't have been less interested unfortunately. I've since Googled it, and some people seem to think it's a ruse to get you back to their office and engage you in some kind of timeshare/property scam, as opposed to you being in physical danger. But I honestly don't know what their endgame was - either way, it wasn't honest.