Oh Urban Dictionary, you are a source of unending hilariousness. If you live in the frosty horror show that is Michigan (currently 14 degrees outside—2 above, with wind chill), you know what a "car booger" is, you just never had a name for it. Big chunk of hard slush, stupid ugly crap behind the wheel, junk that builds up under the fender; these are all ways to describe it, but none so perfect as "car booger." Like all great new terms, it's so perfect it hardly needs a formal definition, but according to the Urban Dictionary, a car booger is:

A chunk of ice or hard slush, usually dark brown, which is found in the middle of, or alongside, the road in winter, having fallen off a passing car. It builds up like a stalactite behind the wheel from dirty road slush being thrown up there and sticking. Also known in some quarters as a slurd.

A Slurd? What a stupid word for car boogers.