My favourite prank call when I was 10:
Me: Hello, may I speak to Mr Walls, please?
Victim: "Er... Mr Walls doesn't live here. I think you've got the wrong number."
Me: Oh, then may I speak to Mrs Walls, please?
Victim: "There's no Mrs Walls either. Like I said, you've got the wrong number."
Me: "Oh, so there are no Walls in your house?"
Victim: "No"
Me "SO HOW DOES YOUR ROOF STAY UP THEN?!?!!1!!"
*hilarity ensues
Me: Hello, may I speak to Mr Walls, please?
Victim: "Er... Mr Walls doesn't live here. I think you've got the wrong number."
Me: Oh, then may I speak to Mrs Walls, please?
Victim: "There's no Mrs Walls either. Like I said, you've got the wrong number."
Me: "Oh, so there are no Walls in your house?"
Victim: "No"
Me "SO HOW DOES YOUR ROOF STAY UP THEN?!?!!1!!"
*hilarity ensues
Sum ergo sum