Rear Admiral Grace Hopper, a pioneer in computer science, shows David Letterman how she illustrates nanoseconds in this highly enjoyable interview.
From her Wikipedia page:
Grace Hopper is famous for her nanoseconds visual aid. People (such as generals and admirals) used to ask her why satellite communication took so long. She started handing out pieces of wire which were just under one foot long, which is the distance that light travels in one nanosecond. [...] At many of her talks and visits, she handed out “nanoseconds” to everyone in the audience, contrasting them with a coil of wire nearly a thousand feet long, representing a microsecond. Later [...] she passed out packets of pepper which she called picoseconds.