Coming from the French to joke, or blague and arriving in London in the 18th Century with the Huguenots it was not long before the local criminal gangs seized on such a good word for a caper. For 180 years it meant armed robbery to Police in Thieves - but it evolved. Blagging was a way of getting something for nothing and the telephone had become the weapon of choice. I could not just hack voicemail, using my voice and a bespoke pretext I could hack your life. I reckon to a large part I still could.
The principles are Charm, Reciprocity, Social Proof, Directed deference and the fear of loss all directed down something as simple as a telephone I can open you up like a can of sardines.
Come and learn to blag (benign blagging is very useful) and more importantly learn the art of the Counter Blag, find out more than they want you to know when you get a funny call.
John Ford was the lead blagger at The Sunday Times from 1995 -2010 until he finally got knicked. Charming the birds from trees was my stock in trade and as Socrates observed "Common Sense is Not that Common"