The Day I Swapped my Dad for 2 Goldfish (+CD): Gaiman, McKean

When a boy swaps his dad for two goldfish he does not really think through the consequences! After all, he is not the only person who can swap stuff. When the boy is told by his mother that he has to get his father back it is not so easily done.
It seems that the father has a pretty high value as he has been traded by one child to the next leaving a trail that the son has to follow.
Where will it all end?