Something like this happened on a British message board I frequent. There is a British consumer electronics company called Amstrad, and in a thread criticising their products a poster appeared calling himself “Alan Sugar”. Sir Alan Sugar, founder and CEO of Amstrad, is famous in Britain - he is in the Donald Trump role in our version of The Apprentice, and has long been a well-known business tycoon.
Anyway, “Alan Sugar” started vigorously defending Amstrad products, brusquely dismissing posters who he said knew nothing about the industry, and did seem to know quite a lot about the business and Amstrad’s history. But the universal reaction was a derisive “Alan Sugar? Sure, and I’m Rupert Murdoch”. One of the more sceptical posters announced that he would call his bluff by phoning Amstrad and asking to speak to the great man. “Alan Sugar” said sure, go ahead. Next day, the poster sheepishly came back into the thread to say that he had called Amstrad HQ, Sir Alan had been expecting his call, and they had had a nice little chat about the thread.