I've seen an increase in strangers messaging me on WhatsApp. When I ask them how we know each other, they tell me a friend passed on my details and said I was a good person to know, they're new to the city etc. If I press on the details, they eventually say something along the lines of "Oh, I mistyped the number I was given - I was meant to text someone else" (in some scenarios they go straight to this line when I ask how we know each other). Invariably they then say "you sound like a nice person, let's chat". Classic scam setup.