"3 piece's of string at a bar" joke

Three pieces of string walked into a bar. The first piece of string went up to the bar and asked the barman "
Can i have three pints of beer please?"
The barman replied "
No sorry mate, we dont serve pieces of string."
So it went and sat back down and the second piece of string walked up to the bar and said to the barman "
Alright mate, can i have three pints of beer please?"
and the barman replied "
Look, sorry mate but we do not serve pieces of string"
So back it went to the table and the third piece of string stood up, tied himself on a knot and fraid the egdes. It walked up to the bar and said "
Can I have three pints of beer please?"
the barman said "
Are you a piece of string?"
and the piece of string replied "
No mate, i'm a fraid knot!!"