A farmer sprayed manure at Oscar-winning actress Emma Thompson after she broke a court injunction to protest against fracking on his land.
Thompson and her sister Sophie - who won Celebrity MasterChef in 2014 - staged a parody of the Great British Bake Off for Greenpeace on the land in Fylde, Lancashire, on Wednesday.
But an angry farmer interrupted the protest by driving around them spraying muck.
Although the actresses were safe inside their Frack Free Bake Off tent, a number of other protestors found themselves hit by the flying faeces, the Daily Mail reported.
Protesters are banned from the site by a high court injunction but the Thompson sisters and other protestors ignored it to carry out their demonstration.
Police officers attended the scene but no arrests were made and Lancashire police said it was for safety reasons.
In a blog on The Huffington Post UK, Thompson explained: “For almost five years, Lancashire has been in the midst of a battle to stop the shale gas industry. And despite huge local opposition, fracking firm Cuadrilla is determined to set up its rigs and drill.
“In August 2014, twenty-or-so anti-fracking nanas occupied the same fields I'm in now - land just outside of Blackpool where Cuadrilla wants to drill - and established cake as an anti-fracking weapon of choice.
“For three weeks, those Lancashire nanas, their children and grandchildren, camped out. And as people passed by they handed out free cake, tea and conversation in a bid to raise awareness of the dangers of the fracking industry that they so strongly opposed. Since then groups like Preston New Road Action Group and Roseacre Against Frack have campaigned tirelessly too, pressuring the local council to block Cuadrilla's bid to drill.
“Their hard work paid off too. Because in June last year, Lancashire council leaders listened to the concerns of local people and said a resounding no to the shale gas industry.
“But this victory was short lived. Just a few months later it was revealed that Greg Clark, the government's so-called 'minister for communities', can now overrule local councils, which could pave the way for Cuadrilla and its rigs.”
She added: “We're breaking Cuadrilla's injunction - the special legal block they took out to protestors off their land - for our Frack Free Bake Off. No doubt there'll be kitchen equipment and flour everywhere. But we'll pack everything up carefully, taking care not leave behind any litter, drilling rigs, toxic fracking fluid or unwanted pollution.”
Despite the interruption, the sisters whipped up a wind turbine cake and a solar lemon cake, the Mail reported.