The hair ball or clump in the tub after someone takes shower or bath. Generally used when you find someone else's, as opposed to calling your own a Tub Wookie.
A few strands of hair or small clump may be called a Tub Ewok
Dammit Gwen! Stop leaving a Tub Wookie in the drain after every time you shower!
Michael, when you leave the shower, do you think you could take the Tub Wookie with you?