No Potatoes

A Kerryman, a Corkman, and a Clareman were in a queue to buy potatoes outside a gorcer's shop.
'Sorry', said the grocer, 'I'm not serving Corkmen today'. So the Corkman left the queue. After a while the grocer reappeared and said, 'Sorry, I'm not serving any Claremen today'. So the Clareman departed. Finally the grocer said 'Sorry, I have no potatoes at all today'. So the Kerryman said, 'That's just typical, serving the Corkman first'.