Overview
How to Get Ahead in Advertising is a 1989 British black comedy fantasy film written and directed by Bruce Robinson, and starring Richard E. Grant and Rachel Ward. The title is a pun and can be literally taken as "How to Get a Head in Advertising".
In the film, an advertising executive has a nervous breakdown and finds himself concerned with the ethics of his profession. In contrast with his moral concerns, a secondary personality manifests itself, being cynical and unscrupulous. A brief struggle between the two personalities leads to the emergence of a third one, but this one is both ruthless and cruel.
Plot
The film is a farce about a mentally unstable advertising executive, Denis Dimbleby Bagley (played by Grant), who suffers a nervous breakdown while making an advert for pimple cream. Rachel Ward plays his long-suffering but sympathetic wife, Julia Bagley. Richard Wilson plays John Bristol, Bagley's boss.
Bagley has a crisis of conscience about the ethics of advertising, which leads to mania. He then develops a boil on his right shoulder that comes to life with a face and voice. The voice of the boil, although uncredited, is that of Bruce Robinson. The boil takes a cynical and unscrupulous view of the advertising profession in contrast to Bagley's new-found ethical concerns. Eventually, Bagley decides to have the boil removed in hospital, but moments before he is taken into the operating room, the boil quickly grows into a replica of Bagley's head (only with a moustache) and covers Bagley's original head, asking doctors to lance it, which is done since nobody has noticed the switch from left to right nor the new moustache.
From Wikipedia (CC BY-SA 4.0).