Some states mandate sitting, while others require standing at the bar to drink. Texans may take up to but not more than three sips of beer while standing. Some jurisdictions require the interior of public drinking establishments to be visible from the street; others specifically prohibit that.
In Iowa it's illegal to run a tab. And don't even think of having a drop after closing hours there - not even if you own the bar. It's hard to imagine the incident that led to Iowa's law stating that if an employee pours water down the drain while a police officer is drinking at the bar, the water is considered an alcoholic beverage intended for unlawful purposes.
Bars and restaurants in North Dakota are forbidden to serve beer and pretzels at the same time. Nebraska bars may not sell beer except when simultaneously brewing a kettle of soup.
If you skip the bar and head to a liquor store in Indiana, you won't find any soda or milk in the cooler. They may, however, sell warm soft drinks. In California, no alcoholic beverages may be displayed within 5 feet of a cash register if the store sells both alcohol and motor fuel. Presumably so you don't confuse your Colt 45 with your 10W40.
Philosophical drinkers in Houston might ponder the fact that it's illegal to buy beer after midnight Sunday but perfectly all right any time Monday, which starts - that's right - right after midnight Sunday.