Though students often disagree about the strictness of University regulations, there is no denying that you can and will get arrested if you're causing a disturbance or are heavily under the influence of an illegal substance. Most cops and University police will issue warnings before an actual arrest, but don't take this for lenience. If any type of law enforcement officer gives you a warning, consider yourself lucky and change your ways. Given OSU's past history of misconduct and rioting, it's understandable that security will come down hard on anyone they believe to be a threat to public safety.
The residence halls strictly regulate access-after 9 p.m., you cannot get into any hall other than your own (or any hall at all, if you live off campus). RAs will generally let you do your own thing, though, provided you're not disturbing anyone else. The best thing to keep in mind is courtesy to those around you; even if you don't have an 8 a.m. class, the girl living below you might. Excessive noise is one of the easiest ways to get caught breaking the rules by an RA, and you can actually be evicted for too many violations. While University police are relatively lax, it's not wise to push the boundaries. Officers will hesitate to arrest an underage student who has had one or two alcoholic beverages, since they would be setting a difficult standard to follow; if you're causing a public disturbance, however, they won't waste any time singling you out. Strictness is nothing to worry about at OSU, provided you keep your partying to a reasonable level.