There is a crazy amount of leniency at the University of Chicago with pretty much every aspect of life except academic integrity and the actual law. Other than cheating or committing a serious felony, you really can’t do anything wrong. Both the campus police and the city police are incredibly lenient with underage drinking. The most they’ll do is break up a party if there is some kind of noise complaint. There is no campus curfew, and you’re free to spend the night wherever you choose. You are not forced to attend any classes, although in some, your grade will be lowered if you are consistently absent. Every RSO (recognized student organization) has its own attendance rules, but as a whole, a majority of them is fairly lax. Some groups like Greek organizations and intramural teams work on a more restrictive schedule where attendance is required.
As far as administration, RAs, and the police go, it’s fairly simple: Take care of yourself, don’t break any major rules, and they won’t bother you. If you break the law or a major school policy, you’re obviously going to get in trouble. However, everyone understands the pressure that the students are under. They’re OK with people blowing off a little steam. As long as you don’t bring negative attention to the University, the administration will let you roam free. Everyone who studies at the University of Chicago is smart and responsible. Those qualities influence the students’ actions enough so that the general student population can sustain some anarchy and independence from both the administration and the campus police.