Paddy goes into a John Lewis department store and asks the shopkeeper, "Excuse me sir, but do you sell potato clocks?"
The shopkeeper looks at him and says, "Are you taking the piss? We sell cuckoo clocks, carriage clocks, grandfather clocks, alarm clocks... what the feck is a potato clock?"
And Paddy says, "I don't know, but I start my new job at nine tomorrow, and the wife said 'You'd better get a potato clock.'"