A string walked into a bar and ordered a beer. The bartender said, "I'm sorry, but we don't serve strings here."
The string walked away and sat down, a bit upset. A few minutes later he went back to the bar and ordered a beer. The bartender, looking a little exasperated, said, "I'm sorry, we don't serve strings here." So the string went back to his table.
Then he got an idea. He tied himself in a loop and messed up the top of his hair. Then he walked back up to the bar and again ordered a beer.
The bartender squinted at him and said, "Hey, aren't you a string?" And the string said, "Nope, I'm a frayed knot."