It is hard to find a joke today without a dirty word or two in it, but here is one.
Two tall trees, a birch and a beech, are growing in the woods. A small tree begins to grow between them, and the beech says to the birch, "Is that a son of a beech or a son of a birch?"
The birch says he cannot tell.
Just then, a woodpecker lands on the sapling. The birch says, "Woodpecker, you are a tree expert. Can you tell if that is a son of a beech or a son of a birch?"
The woodpecker takes a taste of the small tree. He replies, "It is neither a son of a beech nor a son of a birch. It is, however, the sweetest piece of ash I have ever put my pecker in."