You make your way to the giant tree in the living room and marvel at the mountains of presents beneath it. But one in particular catches your little green eye:
A plush Scooby Doo.
On the dog's collar is a tag that reads, "To H. From Santa."
"Not for long," you think.
Cunning as a Grinch, you take the tag from another present (later discovered to be a label maker) that reads "To M, From Santa" and switch it for the tag on the Scooby Doo. You tent your tiny fingers and cackle "Heh heh heh!"
Having heard your fiendish glee, your parents and sisters H and E awake and join you downstairs. "Look what Santa brought me!" you exclaim with a sinister squeak as you strangle the Scooby Doo doll in a surprisingly strong grip.
Now, everyone knows that your innocent little sister, H, loves Scooby Doo. She is his greatest fan. She lives and breathes Scooby Doo and will do almost anything for a Scooby Snack.
After a tense moment, H snaps the silence like a candy cane and bursts into tears. She can't understand why Santa has betrayed her, why there is only pain in the universe. Make no mistake, H lost her innocence that morning.
At this point, the parents intervene by saying Santa told them what presents he was bringing and that he clearly made an oopsie. You are sent to your room with only your Life Savers storybook and your cruel little thoughts.

Scooby Doo restored to his rightful (and bit puffy from crying) owner. M has been thwarted once again.