So when my brother was a wee little lad, my mother was helping him prepare his first presentation. It involved a paradise tract, I'm sure.
Anyway, so my brother, probably about 5 or 6 years old, stands at his first door and makes his little presentation. Except he kind of forgot what he was going to say and kind of made it up on the spot, because what he ended up saying was, "If you'd like to live forever you can have this tract. I don't know what it says, because I never read it."
My mom was very embarrassed and upset. We kids, though, laughed about it for years. Awww, cutie baby brother.
Later, same brother made up a new presentation. He was probably about 12 years old and had decided it was stupid that Mom and Dad made him go door to door and talk to people about something he didn't personally give a hoot about. So he started to say to householders (in a very deadpan way): "Resistance is futile." Until my mom found out and promptly put a kibosh to that.
I just find these to be quite funny. Maybe you had to be there.
But anyway, do you remember really funny presentations made by you, your siblings, or your friends?