"Culchie" is also an Irish term for a simple, impromptu bed, chiefly consisting of planks, hastily slung between the tapered end of an inglenook fireplace and the nearest wall of a farmhouse kitchen. A culchie might be offered to anyone who asked for a bed for the night, who wasn't known to the family (rather like letting someone sleep in the barn). So, this could have become a derogatory term for traveling rural labourers and hence just country folk. However, originally it was just an example of common hospitality as often formerly offered to travellers and those in need.