It is the fusion of two words : shoe and phone. The origin of the term dates back to a fictional invention of the humorous series Get Smart, known in Spanish as Superagent 86, whose character, an incompetent spy, uses it to camouflage a phone under the sole of the shoe. It is also used by Mortadelo, a Spanish comic book character who was also an incompetent secret agent. Since then he has been very joking that spies have a zapatophone.
