That's terrible! But it's a trick that's been used quite a lot in the UK, especially at ATM (hole in the wall) machines. The person standing behind you says 'you dropped something (often a sum of money they've planted there) and as you bend down to pick it up, they grab your ATM card or the money you've just extracted.

Take care, and if someone knocks on your car door, just open the window enough to speak through, never open the whole door.

LTS