How long did it take you to work this one out?

Tommy goes into a John Lewis department store and asks the sales assistant, "Excuse me sir, but do you sell potato clocks?"

The assistant looks at him and says, "Are you taking the mick? We sell cuckoo clocks, carriage clocks, grandfather clocks, alarm clocks... what the heck is a potato clock?"

So Tommy 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.'"