Freshmen have the easiest available nightlife at Carnegie Mellon—hands down. Upperclassmen tend to be the most interested in the "fresh meat" that arrives on campus each year, both guys and girls. While they may not be able to frequent the bars or clubs like the 21-year-olds or the sophomores with fakes, they are invited with open arms to virtually any house, frat, or apartment that is throwing a party. It's typical for girls to get in for free to most house parties, unless they are thrown by girls. Guys aren't so lucky—it's not uncommon for them to be asked to fork over $5. To get into frats, you won't have to pay; you will simply have to know somebody and be on the guest list! For these reasons, freshmen really are lucky because if their intent is to be supplied with cups and cups of free alcohol, these opportunities are made readily available.
After freshman year, most students have acquired an ID in some way, or if not, they are good friends or at least know the people throwing the parties. The parties are usually within walking distance from campus. If the house or apartment is a bit farther or the weather is a bit colder, students often call a cab to take them there, and it is rarely over $8. Split that between the five or six you can cram in a cab, and you do the math. As for the bars, CMU students mostly frequent Shadyside, Oakland, and South Side. Shadyside is the most lenient with IDs, but the other neighborhoods aren't impossible. Most students leave Peter's Pub and PHI bar to their 21st birthdays, though. You have to have some new way to celebrate!