We're so used to many symbols that we don't question them. No entry signs, one way signs, signs for men's and women's toilets...
But I came across one in Ghent that amused me, because it was slightly different.
I've often seen, in Italy, the 'no food in the church' message with a picture of an ice cream.
But in Belgium, of course, ice cream is only one of the two ubiquitous foods.
So the sign gets a picture of a cone of chips, with a big red X through them.