Shuzan held out his short staff and said, "If you call this a short staff, you oppose its reality. If you do not call it a short staff, you ignore the fact. Now what do you wish to call this?"
Hofstadter's "Gödel, Escher, Bach" explains this well in chapter 9 (Mumon and Gödel). I believe the argument goes that by calling it a specific thing you "oppose the reality" of all the other things it also is - no single name will ever suffice. Closed world assumption and all that.