Three strings walk into a bar. The first says, "I'll go up and get us some beers." The string approaches the bartender and says, "I'd like three beers for me and my friends." The bartender replies, "I'm sorry. We don't serve strings here."
Dejected, the first string returns to his friends.
The second string says, "Let me try!" So, it approaches the bartender and asks, "May I please have three beers for me and my friends?" The bartender answers, "Sorry, we don't serve strings here."
Dejected, the second string returns to his friends.
The third strings says, "I have an idea. You guys tie me into a knot and shred my ends." Once tied and shred, the third string goes up to the bartender and demands, "I'd like three beers for me and my friends!" The bartender says, "Sure." Then, he quietly pours the beers.
As the string leaves with the beers, the bartender asks, "Hey, wait a minute! Aren't you a string?"
The third string turns and says, "No, I'm afraid not."
("No, I'm a frayed knot." Get it? It's much funnier when read aloud.)