A string walks into a bar with a few friends and orders a beer.

The bartender says,
"I'm sorry, but we don't serve strings here."

The string walks away a little upset and sits down with his friends.

A few minutes later he goes back to the bar and orders a beer. The bartender, looking a little exasperated, says,
"I'm sorry, we don't serve strings here."

So the string goes back to his table. Then he gets an idea. He ties himself in a loop and messes up the top of his hair. Then he walks back up to the bar and orders a beer.

The bartender squints at him and says,
"Hey, aren't you a string?"

And the string says,
"Nope, I'm a frayed knot."