Humor scene?

Okay, ready or not, here's my answer to the humor challenge, feeble though it is. Somehow it seemed funnier when I first wrote it. Funny is hard!

Holly and Alex stood panting on the dock, watching the boat carrying their classmates get smaller in the distance.
“The ferry left without us. What will we do?” cried Holly.
“My scout leader says that in any survival situation, you should first take stock of your supplies.”
Holly rummaged in her backpack. “I have a camera, my water bottle, and half a smooshed peanut butter and jelly sandwich.”
“At least we won’t go hungry,” said Alex. “I have my keys, a notebook, and a self-inflatable dinosaur.”
“A self-inflatable dinosaur! What on earth are you doing with that?”
“My dad gave it to me. He’s the IT guy at the Museum of Natural History.” Alex looked at the sky. “Storm’s coming. The dinosaur could provide shelter.”
“How big is that thing?”
Alex hefted his backpack on his shoulder. “I’ll show you. If I remember correctly, there’s an empty field at the end of this street.”
The two trudged past tourist shops and up a hill to a grassy space surrounding a lighthouse.
Alex took a large rubber rectangle out of his backpack and uncocked the self-inflating mechanism.
It hissed and whistled and wheezed as the dinosaur took shape. The head was as big as Holly’s bedroom. The neck looked like a tree trunk. The body was as big as a school bus.
“A tyrannosaurus!”
“Indeed,” said Alex. “Dad thought it was an appropriate choice for his son, Alex Rex.”
There was a sudden gust of wind from the sea. The dinosaur bucked.
“Don’t let it blow away!” cried Alex, wrapping his arms around its neck.
Holly grabbed a floppy foot.
They tumbled across the field, bounced over the trees, and came to a shuddering stop against a tall stone arch.
“The dinosaur’s head stuck in the entrance to the labyrinth at the top of the island,” announced Alex.
“A-mazing,” said Holly.