Refers to where some
lazy jacka** scrapes/brushes the icy white stuff off his car only enough to let him see out the windshield before driving away on a cold morning. Not only does this prevent him from safely "seeing and being
seen", but it also means that huge clumps of snow
will periodically fall off his vehicle and splatter onto the plowed roadway, messing up the lane where other motorists have to travel.