I've once seen a motorcycle cop doing that in rush hour traffic on the 405 freeway here in So Cal. I've even seen idiots pull up to Police directing traffic at the OC Fair on their phone only to have the Officer yelling at them to get off the phone. Strangest things I've seen people do while driving (in addition to the usual make up, shaving) has been reading a book (long time ago), and playing a guitar (in more recent years)..