A piece of string walks into a bar

The bartender glares at him. "We don't serve pieces of string like you here."

"What? I just want a drink!" the string says.

"Get the hell outta here!"

The string leaves, dejected. On the street, he runs into another piece of string.

"Did you just get thrown out of that bar too?" the second piece of string says.

The first piece of string nods.

"Here, let me show you a trick."

The second piece of string then ties the first piece of string in a large knot, then frays either side of him. The first piece of string walks back into the bar.

"Hey, aren't you the string that just came in here?" the bartender yells.

The string shakes his head. "Nope, I'm a frayed knot."