In the Wild West of USA, in the late 19th century, a Dutchman went into a bar,
took out his two guns , placed them on the table and ordered drinks for himself
and the twenty other people there and said "When I drink, everyone drinks" 

Everyone grateful accepted a drink. He finished his drink and ordered another
and said "When I have a second drink, everyone has a second drink" .

Again everyone gratefully accepted. When the big bill came, the Dutchman stood up,
fired his pistols in the air, paid for his two drinks and said " When I pay, everyone pays".

 

That is how the proverb " going Dutch" came into being.