A piece of string walked into a small town on a hot, dusty day.
He was thirsty, so he sauntered into the first establishment he
encountered and asked the waiter for a glass of water.
"Sorry", said the waiter, "we don't serve strings here."
Discouraged, the string walked out. A little further down the
street, he met a stranger.
"You look hot," said the stranger. "Why don't you go into that
cafe and get a drink of water?"
"I tried that," said the string, "but the waiter wouldn't serve
me anything because I'm just a string."
"No problem" said the stranger. "I'll fix you up." He grabbed
the string, tied him in a bowline and frayed his ends. "Now try it."
The string slipped back into the cafe and asked the waiter for a
glass of water. "Hey," said the waiter, "aren't you the piece of
string that was just in here?"
"Nope," retorted the string, "I'm a frayed knot."