Stringing You Along

A piece of string walks into a bar. The bartender eyes it carefully and says suspiciously, "Say, aren't you a piece of string?"

"Yes, I am. Why?"

"Well, we don't serve pieces of string here. I have to ask you to leave."

The piece of string leaves the bar, but he doesn't give up. He ties himself into a knot, frays his ends and goes back into the bar.

Once again, the bartender looks him over and says, "You're a piece of string, aren't you?"

"I'm a frayed knot."