You have a bottle?

A guy told me this joke that I found really funny. It goes like this.

Two shopkeepers were getting bored so they decided to play shopkeeper-customer. One guy was the shopkeeper and the other came as a customer "Can I have one bottle 'gur' please." The other guy said "You idiot, gur is not sold in bottle, come back and ask for one kg gur."

The guy comes back once again "Can I have one kg gur in a bottle". The first guy was really frustrated, "You can't do it, just sit and watch, I will be the customer this time".

He comes as a customer and asks the guy. "Can I have 1kg gur?" The second guy looks at him and said "Have got an empty bottle."

I thought the joke was over but I experienced the punch line of the joke yesterday when I saw that the gur I had was in a state where I can be poured in a bottle.