A new manager starts at the sewage works.
After reviewing the personnel records, he sees that the longest serving worker, Fred, has not taken a days leave in the forty years he's been there.
He calls for the work supervisor to ask about Fred and the supervisor explains how old Fred is a dedicated worker. No one knows the sewage system like he does, and he really is the hardest working man in the place.
The manager asks to meet Fred, and the supervisor explains how they will have to go to Fred rather than him come to them.
Once kitted up they descend into the network of sewers beneath the city and meet up with Fred.
Fred is flattered that the manager has come to see him and regails him of the history of the sewage system.
He then suprises him by saying he can tell where each individual poo comes from!
"Prove it!" Says the sceptical manager.
So Fred points out a floater and says, "That's from the butchers".
"How do you know?" asks his boss.
"Simple! its covered in sawdust. The one next to it is from the iron mongers, see it glittlering in the light? Thats the iron filings in it. The one behind it is from the sweet shop, you can see the Hundreds and Thousands its covered in. And that one there" He points to a plop floating along, "That one is my wifes'!"
"Oh come on!" says the manager, "How can you possibly know that one is youre wifes?"
"Simple" says Fred "Its got my sandwhiches tied to it!"