I believe it was in the early 1980s or so that the Bell Telephone people came up with their catch phrase "Let your fingers do the walking - through the Yellow Pages." The phrase was intended to mean that you could look it up first in the Yellow Pages and save lots of time and money you'd otherwise spend looking for stuff.
For the clueless, in US phone books it has been traditional for the "Classified Listings" for business to be printed on Yellow pages, and the sale of ads/listings was marketed pretty aggressively.
Numerous "spot ads" referring to the "fingers walking" theme were sprinkled among the Yellow Pages ad/listings to remind people that "you too can advertise."
In the first issue of the Wichita Kansas phone book in which the Bell folk relented their previous policy and printed ads for "Massage Parlors," someone placed immediately below the largest "Parlor" ad - the standard filler ad:
"Imagine 20 million walking fingers."
I was told, but never could confirm, that the person responsible was fired, although it would have been hard to select a more appropriate one of their ads for that page.