Being a lawyer and a life long amateur historian, I was vaguely aware of the law code of Ur-Nammu. He was a Mesopotamian king about 4 millennia ago. His laws pre-dated the more famous Hamurabi's Code by three centuries. Well, recent discoveries have shown just how advanced that civilization was. They had a statute to deal with paying your bar tab:
[T]he fact that this is the earliest known edition [of the law code of Ur-Nammu] allows researchers to compare it with later copies and see how it evolved. For instance, the copy sheds light on one of the oddest rules governing what you should pay a "female tavern-keeper" who gives you a jar of beer.
Apparently, if you have the female keeper put the beer on your tab during the summer, she will have the right to extract a tax from you, of unknown amount, in winter.
"If a female tavern-keeper gives [in] summer one beer-jar to someone on credit its nigdiri-tax will be [...] in win[ter]..." (Translation by Miguel Civil)
No word yet if Borepatch's beer tab in ancient Mesopotamia was as much as he used to run up at Pat's Tap Room in college.