News from Belgium that chips and mayonnaise have been thrown at the Belgian PM shows there's a growing appetite among the hoi polloi for using food in political protests.

In olden times it was gauntlets that were thrown at the feet of one's adversaries, followed by pistols at dawn. Now all that has changed, doubtless because it's too genteel, too discreet and way too slow a way of achieving the desired result.

We'd got used to people in Arab countries showing the soles of their shoes to show contempt (shoes are deemed unclean, lowly and thus beneath contempt), though when it comes to politicians protesters actually throw the shoes, as happened to former US President George W Bush, or use them to slap such potent items as the fallen statue of Saddam Hussein.

However, food is increasingly being used for serious political protest, presumably because it's more visible and can make an unholy mess that's difficult to clean off clothes, making for dramatic and humiliating images to be disseminated around the world on telly and social media. In 2008 Labour deputy PM John Prescott had a egg thrown at him - a move echoed in September, when the Scottish labour MP Jim Murphy was egged on the back during the Referendum campaign in Glasgow. And earlier this year, Ukranians chose to throw spaghetti, of all things, on the Russian consulate in Odessa during the military interventions in their country. It was explained that in Russian, the expression "to hang noodles over someone's ears" means to "pull someone's leg": by throwing spaghetti the protesters were implying that the Russian media's reporting of events wasn't balanced or serious.

Last year, protesters at President Obama's "outrageous spending" were urged to post bags of marshmallows to their congressional representatives to suggest they were going soft in opposing them.

Food protests had already become a speciality in Belgium before this week's incident. Microsoft founder Bill Gates was custard pied in 1998, as was former French president Nicolas Sarkozy in 2013.

Now they have become less slapstick. Chips and mayonnaise are, of course, Belgian specialities and the symbol of this proud nation. By using the prized culinary items to draw attention to their anger at the PM's proposals to raise the retirement age in Belgium to 67, they're doubtless telling him he's betraying his country. This is a very specific form of food protest, possibly unprecedented in Belgium (though France and Spain are dab hands at it).

It's only a matter of time, surely, until some hapless Scottish public figure complains they've been porridged.