We looked at this in PR class today; it's a classic.
This video features Guy Goma, who was waiting in the reception area of the BBC to be interviewed for a position in IT, when he was mistaken for Guy Kewney, a British tech expert, who was waiting in another room, preparing for an on-air interview at the BBC.
Cue the switcheroo: a stagehand gets them confused and - presto - Guy Goma is on-air and, at first, visibly shocked that he's being asked to pontificate about about the Apple vs. Apple computer case.
He gamely plays along and, as he goes along, his confidence increases, and he actually does quite well. Proof that media relations is easy!
Unfortunately, Goma never got the job for which he applied. However, he did get his own website, so it wasn't a total loss.