Féar Gortha or Hungry Grass and Fear Gurtha or Hungry man.

Féar Gortha (fear gur-tha) or Hungry Grass origans can be traced back to the Irish famine, its a  patch of cursed grass that make a person hungry once they cross it. Oral traditions say that these patches of ground were created when a famine victim died on that spot. but it was only the victims that did not recieve absolution before they died, then faeries then plant the hungry grass on this spot.

It is not just that it makes you hungry as you step on it, but if you did not get something to eat immediately you could drop dead on the spot and it doesn't make a difference if you had just eaten a meal.

Then there is the Fear Gurtha (far Gur tha) the Hungry man, he travels the road with the disguise of a tramp with rags for clothing begging for alms. If you were kind and gave him alms then you will be lucky for the rest of your life. On the otherhand if you ignored him, you were guaranteed to suffer some disaster and would spend the rest of your life in poverty and hunger. There is a tradition when eating outside in certain parts of the country of sprinkling crumbs on the grass after eating, to show the faeries that you are not a mean person.

So when a sign says Keep of the Grass, there might be a reason in Ireland.