<p>Actually a lot of public schools probably do have some rules on overnight guests of the opposite sex. There was a time in which the colleges used to act as parents. Whether they are enforced ever in this day and age is an entirely different matter.</p>
<p>At my school and at others that I visited friends at the offical rule was no opposite sex guest past 2AM. Entrance into the dorms after midnight required showing a student ID and the resident had to sign in the guest. In fact at my alma mater, there was an effort by the campus security to begin enforcing that rule in the fraternity houses…it was a pain in the ass and there was a lot of complaining.</p>