Later, at home, my Google search for "Jewish Squirrel" only turned up the MySpace page for a female resident of Bangor, Maine. However, "Jew Squirrel" led me to a YouTube clip of comedian Richard Lewis speculating that Larry David's Jew Squirrel diet of grains and fruits and nuts could be the cause of his numerous daily bowel movements.
In any event, it leads me to believe that this truck is being driven by a fan of the Curb Your Enthusiasm TV show, or is himself a practitioner of the Jew Squirrel Diet. In which case, he was probably in a hurry to get to a bathroom.
Here's the "Jew Squirrel" video: