This Watermelon Sleeping Mask is currently sold out and has a 5,000 person wait list. The company that makes it is called Glow Recipe and if you're wondering what, exactly, is so special about this product...
According to Glow Recipe’s website, watermelon rind and flesh is traditionally used in Korea as a soothing ingredient and is full of skin-restoring vitamins, antioxidants, and amino acids. The mask also includes glycolic acid and lactic acid to gently exfoliate, while hyaluronic acid hydrates, and peony root brightens. [Source]
And yes, you are supposed to sleep in it.
It retails for $45.