Janey Godley’s complaint that she thinks she was ripped off by the people who made the new Irn-Bru ad has caused a stir in comedy circles. It is not the first time a comedian has allegedly had input into an advertising campaign and not been given credit. Or, in some cases, paid.

Just to recap, Godley auditioned for a role in the latest Irn-Bru ad and during the audition, referring to a man's bare bum, the Glasgow stand-up quipped “crack on”. She mentioned this on Facebook at the time on March 4. When the advert appeared this week Godley’s two words were used onscreen.

The response from those involved was to say that a number of comedians auditioned said similar things. Some apparently also said “bottoms up” – which although more obvious feels like a better line to me. Which maybe explains why I’m not in advertising.

So the answer is that they didn’t get it from Godley because others had the ideas too. Putting aside the question of whether that sounds like they still got the idea for nothing, that still raises the classic problem in comedy of ownership of jokes.

When a major news story breaks it is inevitable that some people are going to come up with the same line independently. When the last Pope died there was a joke flying around from different sources that the new Pope was going to be chosen on Pope Idol. I know. I made it myself independently. There have also been various similar jokes in recent years which were basically a play on the words papal and Paypal – there was one of Newzoids the other night.

So how do you prove a joke is yours? Some comedians have said that they use social media as a kind of ‘date stamp’ device, proving when they have coined a quip. That’s what Godley did. But it doesn’t stop someone else saying they came up with the gag earlier but didn’t post it. In fact the argument can even work the other way – they may claim they didn’t post it on Twitter because they didn’t want the joke to be stolen.

Over the years advertising seems to have been inspired by comedy. There was the Sugar Puffs ad that had echoes of The Mighty Boosh’s ‘crimping’, while Vic and Bob’s crazy ideas also seem to find their way into commercial campaigns. Vic and Bob also recently claimed that they had had an influence on another light entertainment duo: “Ant & Dec have always nicked stuff off us,” Reeves told the Guardian. “We met their writers, they said they just trawl our stuff and adapt it. The problem is they’re a lot bigger than us, so people think we’re copying them.”

And In 2009 Micky Flanagan’s “Out Out” phrase appeared on a 118 118 advert. Even the Advertising Standards Authority said in a response to a complaint from Flanagan’s agent that “the advert clearly mimics your client's idea". But while Flanagan clearly popularised the phrase it is harder to prove that he invented it.

Godley is not a troublemaker as someone suggested. She sounds like she has a right to be furious. If other auditionees also said it she should be furious on their behalf too. I’m not an intellectual property lawyer, but Godley has evidence that she said it and then evidence that they later used it. If they didn’t get it from Godley the onus should surely be on them to say where they did get it from – and settle the matter with them accordingly.

Watch the Irn-Bru ad here.