Another thing is you can't do things with another student org thats on campus with an off campus student org, so if you try partying with a sorority they could be sanctioned too. You can't advertise or recruit around campus because that's unauthorized. Can't post flyers in the dorm elevators, the RAs will rip it down. Can't rent classrooms out for recruitment events or participate in anything at the beginning of the year when students learn of these things. Universities typically make it easy to kick you out of the school if something goes wrong at an unregistered org event and make sure you are fully legally liable. Something going wrong could just be a freshman stumbling back a little drunk and getting in trouble with an RA, doesn't have to be a serious thing to ruin your life.