So 3 pieces of string walk into a bar.
First one walks up to the barman “3 beers please”
Barman says “sorry, we don’t serve string in here”
Second one walks up to the bar “3 beers please”
Barman gets angry “oi, I told you we don’t serve string”
Third one messes up his hair, twists about, coils himself up, goes up to the bar “3 beers please”
Barman peers at him “here, you’re not one of them pieces of string are you?”
“No I’m a frayed knot”
That’s just taking the pith