Dairy Siphon

Twilight stared daggers at the carton of milk floating in front of her. She was closely inspecting every angle of the moderately-sized milk container, checking every inch of it for even the slightest blemish.

In reality there was nothing particularly special about the carton, it contained nothing but ordinary milk(2% because Twilight is on a diet) and the structure was mere plastic. To Twilight however, it was the source of a terrible mystery that had kept her awake for weeks, her solar powered pony battery the only thing keeping her alive, let alone conscious.

It wasn't the material that housed the liquid, or even the liquid itself, but rather the milk to air ratio that had her seething in anger.

Just yesterday she had gone to the marketplace and purchased a brand new gallon, a ritual she had completed hundreds of thousands of times. Once she had gotten home she prepared her dinner, and poured herself one glass of milk, one, exactly eight ounces, no more, no less.

But now, a mere day later, the carton was half-empty.

"There has to be some sort of rational explanation for this." Twilight said aloud, though by this point in her period of sleep deprivation all she could manage was a myriad of irritated murmurs.  She sluggishly stumbled her way over to a small video camera that was propped up exactly across from the refrigerator. Using her magic, she opened the tiny screen and pressed the "play" button.

She sat there, in front of the camera for eight hours, analyzing every single pixel, taking notes at even the tiniest discrencies. As always, her efforts yeilded no results