Ok wtf is this stuff?

So I'm leaving work tonight and I get to my car to find it covered in this... confetti type substance. It's like it snowed shredded cardboard just on my car. None of the cars on either side of my car had this crap on it, why mine? And just WTF is it??

I still have no idea but it makes taking driving pix difficult when the flash reflects off this crap.