Do mythical creatures have childhoods, too?

My kids believe in a number of mythical and magical creatures and symbols that help them to navigate through their days as children.  Things that helps them to make sense of the world around them, and keeps them feeling safe.  The Easter Bunny, Tooth Fairy and Santa, bring them special things.  Gargoyles keep their bedrooms safe from predators and bad things.  dream Catchers grab hold of the bad dreams before they enter the children's heads.  The Sandman fits in there somewhere, too.  They were first introduced via an episode of Baby Looney Tunes where Baby Daffy keeps trying to see the Sandman who puts sand in the corners of his eyes while he sleeps.

Unlike Santa and the Easter Bunny, the Sandman's appearance is left more to the child's imagination because of it's obscure popularity.  And it's those types of things that torture the mind of Teensy.  She likes to have a clear picture in her head of the things lurking in her bedroom in the middle of the night. 

"Mom?  Is the Sandman big or little?" 

"I don't know, baby.  I've never seen him." 

"I did, on a movie."  *

"Oh yeah?  Was he big or little?" 

"He started little, then got big."

"Like he grew up?" 

"Kinda."

"Why?  Was he in your room last night?"

"Yeah.  I think he's big."

"I didn't hear him so he must not be too big." 

"Maybe he's medium."

"Maybe.  I didn't hear him."

"Maybe he's still little."

"Hmm.  Could be."

She crinkled her nose in thought and was silent for a few minutes.  Then out of nowhere, the room got brighter and she stated with the seriousness only a child could pull off...

"Maybe he's big with marshmallow feet.  you can't hear marshmallow feet!"

...and she tiptoed on her little blue stool to demonstrate her point. 

* I am still wracking my brain as to what "movie" she is referring to.  If  you come up with it, please do let me know.