A KFC advert has been banned for using the phrase “What the cluck?!” in an advert for a £1.99 lunch – sparking a row over whether people will understand where the phrase derives from.

Industry watchdog the Advertising Standards Authority (ASA) said the advert, which was spotted at bus stops and other locations throughout September, was “likely to cause serious and widespread offence” and that it was “irresponsible” for the ads to appear where children could see them.

Ads seen in the Metro and Sun newspapers were similar to the bus stop posters but featured the elongated word “cluuuuuck” instead – they have also been banned.

The ruling has prompted debate over whether people will associate the phrase “what the cluck” with the expletive it obviously rhymes with.

KFC said it disagreed with the claim that the advert included a word which was a substitute for an expletive, saying the phrase “what the cluck?” represented “the customers’ response to a great value KFC deal”. The onomatopoeic reference to the noise of a chicken was used in context and wholly relevant to the deal, the product featured and the brand, the fast food chain said.

The ad was a continuation of a KFC campaign which had launched on TV and radio and featured the same phrase and real sound effects of a chicken, in place of the word “cluck”. 

KFC argued that the use of the word was a tool to visually represent the sound effects of a chicken, and that it did not believe there was any ambiguity in the typeface or arrangement of the wording that could have allowed for it to be interpreted as an expletive. The chain also said it was unlikely that children would make any connection between the words “cluck” and “fuck”.

But the ASA disagreed. In a lengthy and detailed assessment of the phrase and its linguistic roots, it said it understood that the use of the word “cluck” was a reference to the sound of a chicken and was relevant to the product advertised. It also acknowledged that the ad did not contain the expletive “fuck”.

But the written word “cluck”, as used in the poster and press ads, would be interpreted as alluding specifically to the expression “what the fuck”, it said.

In a statement, the ASA said: “We considered that fuck was a word so likely to offend that it should not generally be used or alluded to in advertising, regardless of whether the ad was featured in a newspaper which had an adult target audience.

“We also considered it likely that parents may want their children to avoid the word, or obvious allusions to it. The poster was likely to be seen by people of all ages and while we recognised that the press ads would have a primarily adult audience, they could still be seen by children.”

J C Decaux, which owned the bus stop poster site, apologised for the oversight and said it had advised its team that in future any allusion to a swear word should be escalated for approval. 

Meanwhile, Metro said its newspaper was not published for, or targeted at, children but was for an adult audience aged 18‒44 who lived in metropolitan areas. It added that the ad was not published on the front page of the newspaper. While the Sun said it wasn’t aware of any complaints in relation to the ad, and therefore did not have any evidence to suggest that its readers found it offensive.

The advert is not allowed to appear again in its current form and ASA said it has told KFC to “avoid alluding to expletives that were so likely to offend”.