An iPod-using pedestrian (typically of New York) that unknowingly risks becoming street pizza by attempting to adjust the perfect song and volume intensity while wandering into the street/against the crosswalk signal.
My cabbie almost flattened an iPod Zombie on the way to the airport.
An elderly couple that frustrates tailing automobiles by driving extremely carefully or slow, typically in an unpassable situation. Also can be used in the singular, regarding only "Ma" or "Pa" or similar old fart, depending on the gender of said driver.
I was making good time on that off-road until I ran into Ma and Pa Kettle going frickin' 25 mph.