Cassie's "Hide-Out"

So there I am, walking down the hallway with a HUGE load of clothes...and I stumble upon THIS:

Ok, so I can't get around it, so I decide to take a look and see what the kids are up to:

Hmmm..I think I see something in there. What is this thing? A beaver dam to keep the laundry from getting done?

Ahhh, so there is the little culprit! She was so proud of herself. She build it "by mySELF" haha