Has there ever been a more condign metaphor for what Britain has become than the milkshake protest? These shallow treats often masquerade as healthy owing to a barely discernible patina of fruit in their flavouring.

In truth, they are a gooey assemblage of sugar and chemicals that form the perfect accompaniment to a smoochy big beefburger when you’re still howling from last night’s debauch. That a milkshake has become the icon of political protest sends all the wrong messages about the UK’s commitment to healthy lifestyle choices and our attitudes to climate change.

The deployment of airborne comestibles to register anger at the political elites has a long and noble history. Not long ago, a swollen political ego could expect to be met with eggs and fruit, signifying healthy choices even in our edgier neighbourhoods. In Scotland, the robust larder of Gregg’s the baker has occasionally provided the arsenal for alfresco protest. Admittedly, flying sausage rolls and steak bakes may not be everyone’s idea of a responsible, health-conscious political protest but they’re not the worst, and you’d be supporting local jobs.

Dugdale’s first keynote lecture could introduce the concept of decency in political protest

You wouldn’t catch Swedes or Italians launching something as unedifying and barren as a milkshake to puncture the pomposity of politicos. Scandinavians would use something brawny and probably reinforced by fibrous stuff such as pulses and grains, thus enhancing its potential to be reused in hospitably low temperatures. The Italians, experienced in the art of sustainable political protest, would ensure that nothing went to waste and would take great care in the preparation of what was to be thrown. When they hung up the body of Benito Mussolini they did so from meat-hooks and with locally sourced rope, thus conveying positive messages about sustainable rural economies. And in suspending it upside down they were able to add a wee Mediterranean flourish too.

I once saw the men of a rural community in northern Italy hunt down and kill a wild boar. They honoured the beast by ensuring that none of its parts was wasted and took great care to remove its bulbous testicles. I like to think that these would have made a fitting choice for a fleshy but nutritious act of sedition.

In 2002 Barcelona FC supporters launched a pig’s head at their former player Luís Figo, who had betrayed them by departing for Real Madrid, their eternal rivals. Pictures of this protest travelled round the globe, providing a welcome boost to the Catalan farming and food industry.

In Britain, meanwhile, we have been reduced to chucking artificial and coronary-inducing confections from global fast-food emporiums. The next generation of political protesters is watching these scenes. How can we expect to teach them about responsible methods of throwing stuff at politicians?

In keeping with Scotland’s aspiration to develop a sustainable and green future, I think we can forge a much more socially responsible path in the ways of political protest. The John Smith Centre for Public Service, which operates out of Glasgow University’s school of social and political sciences, recently appointed the former Scottish Labour leader Kezia Dugdale as its director. Essentially, this is an outfit that enables middle-class busybodies to get into high positions in politics without having to get their hands dirty by joining their local branches and actually meeting the people. They loftily proclaim that they want to introduce decency and respect in politics. On completion of the courses presumably you get a certificate in hand-wringing and the skilful use of PowerPoint slides.

However, I feel that there is a way for the John Smith people to make a valuable contribution to Scottish public life. In Dugdale’s first keynote lecture to the next generation of spin doctors, government advisers and political scientists, she could introduce the concept of decency in political protest. After all, if Scotland is to gain its independence it must show the world that it is deserving of it. It won’t do this if pictures of hoi polloi launching milkshakes at politicians are winging their way round the world.

Remain voters missed a trick with their milkshake. Brussels sprouts would have looked more European and sophisticated

The John Smith Centre seeks a kinder form of political engagement but sometimes there’s nothing else for it but to chuck things at our elected representatives. The thinktank’s role would be to ensure that this is done in a more refined way, using sustainable produce from local outlets. Really, how can you make an inclusive and environmentally friendly protest by purchasing products from the corporate chainstore running-dogs of global capitalism?

If you feel moved to projectile political vehemence, then try to source your object from a local provider. This should preferably be vegetarian in nature, though in outlying rural communities, perhaps nursing a faltering economy, the body parts of dead farmyard animals that can’t be eaten, such as heads, balls and tails, could be encouraged.

Next, use fruit and vegetables that are in season all the year round, such as cabbages and onions. Think, too, about what kind of message you’re sending when you launch these into the coupons of politicians. I feel that Remain voters missed a trick with their milkshake escapades. Brussels sprouts would have looked more European and sophisticated.

An ancillary benefit is that such foodstuffs can be swept up afterwards and used for soup or animal feed. Thus the diurnal eco-churn is maintained and the delicate balance of nature is respected.

• Kevin McKenna is an Observer columnist