Wiktionary
tube sock
n. A one-size-fits-all sock, having a plain tubular shape rather than one designed to match the contours of the foot.
Usage examples of "tube sock".
He also saw that her face was white as a tube sock and her eyes near black with fear.
Bass's gradebook when he was called on to report the exact length of a tube sock he was supposed to be measuring and was discovered to be taking a nap instead.