SUSANNA Reid clashed with Mr Broccoli as they discussed vegan protests on today's Good Morning Britain.
The journalist, 48, called the activist "absurd" for dressing like a vegetable while trying to tackle the serious issue of climate change.
Despite Susanna's co-host Piers Morgan usually being the one to lose his rag, Susanna seethed: "Your argument dressed up as broccoli strikes me as so absurd.
"That you're wearing a costume but you're trying to get a serious point across about veganism."
Susanna then questioned Mr Broccoli's motives, adding: "Are you actually not part of Animal Rebellion and Extinction Rebellion at all but somebody who's trying to send up the whole movement?
"Because I'm not sure you're gonna win anybody over dressed as a broccoli trying to make a serious political point about how to stop climate change by changing your diet."
Mr Broccoli then responded: "I hear what you’re saying and we’re in extremely hot water about this.
"It's going to go pear-shaped."
Piers then chimed in, asking: "Do you practice what you preach when it comes to the environment, at home?
"Do you have televisions and electrical devices?"
Mr Broccoli - who was arrested at the Animal Rebellion protests on Sunday but released without charge - then mocked: "No, I’m just a broccoli."
Unsurprisingly, his comment didn't go down well with Piers and Susanna who slammed their guest's lack of knowledge about the science behind plant-based eating.
Piers raged: "You have to explain to them why you think a plant-based diet is going to be effective. If you don’t know the science, how can you do that?"
"Well, I am just a broccoli,’ the activist said before taking a banana out from his jacket pocket and pretending it was a phone.
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Piers snapped: "The trouble is Mr Broccoli, had you made a very coherent, powerful, science-based argument, you would have had a real impact.
"You would have a lot of attention through the way you dressed up for your cause, but to come on here and just be an idiot makes us think you’re just an idiot."
Extinction Rebellion's climate-protest campaigners have planned two weeks of disruptions across London, which began on October 7.
Thousands of protesters brought the capital to a standstill last week as they blocked roads and bridges, forcing ambulances to be diverted and causing mayhem for motorists.
Some protesters handcuffed themselves to cars or glued themselves to government buildings.
Activists occupied London City Airport, with a paralympic athlete gluing himself to a BA plane and others attempting to stop flights taking off.
Meanwhile militant vegan offshoot Animal Rebellion took over Smithfield Meat Market causing traders to lose thousands of pounds in just one night.
Yesterday police said 1,445 people had been arrested so far as the mayhem continues this week.
The leftie XR group is calling for a reduction in air travel and wants the Government to reduce greenhouse gas emissions to net zero by 2025.
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