Very common scam all over Asia, even in Europe/US where they ask for itunes card of similar shit...
1.They basically entice you with very nice pics of gals.
2. Tell you to meet at a place.
3. When you got to the place, they call you and ask you to go to the nearest convenience store to buy a gift card to pay her in advance. (they always find some excuses like, they don't carry cash at their place because they are scared of the police raiding their place etc...)
4. You go and you buy the card, you scratch the number on the card, and they ask you to take a picture of that serie of number.
5. You give the number -> You've been scammed.
6. They block you on line/wechat.