Still Not Funny

Talking to Joe in the car today.
Joe: "A big duck up on a tree." Is that funny?
Dad: Not really.
Joe: Tell me how to be funny.
Dad: It's not that easy, really. Funny's hard.
Joe: Well, how can you be funny?
Dad: Well, you try to find out what other people think is funny, and then do something that's similar but different enough so it seems new. And it has to seem funny to you, too.
Joe: What I think is funny is a ghost and some poop.