The Floating Duck

I once stayed in a nice little guesthouse with a very small rear garden, of which the owners were nonetheless very proud. In the centre was an old bath with a single plastic duck ......

One morning I got up and out of my bedroom window saw the owner digging furiously at one end of the bath. That evening at dinner, I asked him why he had been digging under the bath, and he said:

"Well, my wife says it isn't level. The duck keeps floating to one end ......"