A duck walks into a pub at lunchtime, waddles up to the bar and orders a sandwich and a beer, and settles down at a table, opening his newspaper. He does this every day until the astonished bartender finally asks him what he does. "I'm a plasterer", replies the duck, "I work at the building site over the road".
Later in the day the ringmaster from the circus comes in to the pub for a beer after work. The bartender raves about the duck - "he comes in, orders a beer and a sandwich and reads the paper! You should have him in your circus!"
The ringmaster is keen, and so the next day the bartender tells the duck that there could be a job for him at the circus. "The circus?" says the duck, "you mean the one that just set up in the park?" The bartender nods. "With the big canvas tent with flaps in the side so people can get in and out?" "Yes, yes" says the bartender.
The duck looks puzzled. "What would they want with a plasterer?"