Ham on Wry

THREE STRINGS WENT INTO A TAVERN. The first string went up to the bar and ordered drinks. The bartender said, "Sorry, we don't serve strings." The second string went up and tried, but got the same rebuff, "Like I told your friend--we don't serve strings!" The third string said, "I'll handle this," went outside, tied a knot near its top, ruffled up its ends, came back inside and up to the bar. When the barkeep said, "Are you a string?" it answered, "No, a frayed knot," and got their drinks.