It is not a good idea to drink or do drugs openly on campus, or at least not outside. Drinking is technically not allowed in dorms on campus, nor are drugs allowed in private dorms (alcohol is allowed in some private dorms), but students definitely both drink and do drugs in their dorm rooms. Generally, though, the police are only called if the RAs decide to call them.
At the football games, be sure not to carry alcohol in your purse or in your boots, because many students are searched and patted down. Many people get drunk prior to the football game at a tailgate party or house party, and then they just arrive at the game drunk. The thing that UT is known to be most strict about is parking, and UTPD loves to write parking tickets.