51: Major bus line that runs from the Berkeley Marina, up University Avenue and down College Avenue and Broadway to Jack London Square/Alameda. You will likely be riding it a lot.
AC Transit: The transit agency that runs the bus system in Alameda and Contra Costa counties.
BART: Acronym for Bay Area Rapid Transit, i.e., the heavy-rail/subway system that runs throughout the Bay Area, but goes to bed early. The closest station to campus is in downtown Berkeley, at Center St. and Shattuck Ave., and lines run through Oakland, San Francisco, and various outer suburbs.
Berkeleyside: Run by longtime journalists, it's the go-to local website for Berkeley news.
Cal Day: Cal's big annual festival — set for, ah, April 20 in 2013 — in which the campus opens itself up to the public and potential students for a day of free events, museum admission, lectures, and more. Also a really good day to stock up on free Cal keychains, stickers, and other schwag.
co-op: Affordable shared housing, mostly for students. Countercultural analogue to the "Greek" system. Famous for food orgies, naked pot wash, and Chik patty cuisine.
Daily Californian: Better known as the Daily Cal — and, ironically/depressingly no longer daily, thanks to that darn recession — this is UC Berkeley's excellent, independent student newspaper, which you can pick up in boxes all around campus.
East Bay: Technically speaking, the huge swath of land that lies east of the bay and extends roughly from Crockett to the north and Union City to the South. Most people use it to mean Berkeley, Oakland, and the few small cities that lie just adjacent.
East Bay Express: A, ahem, popular alt-weekly newspaper covering the East Bay that's been around since 1978, is independently owned and operated, and is known for award-winning investigative reporting, indispensible arts and culture coverage, restaurant and movie reviews, events listings, and terribly imaginative special issues. (Hint: You're holding it in your hands.)
Frat row: The stretch of Piedmont Avenue between Dwight and Bancroft ways that contains the cluster of fraternity and sorority houses, and has the highest concentration of alcohol poisonings during rush week.
Free Speech Movement: Believe it or not, it wasn't that long ago that UC Berkeley banned political speech on campus. But during the 1964-65 school year, that all changed because of a massive student protest, known as the Free Speech Movement, led by student leader Mario Savio.
Frisco: A term you should never, ever use to describe San Francisco. (See "The City")
GSI: UC Berkeley shorthand for "Graduate Student Instructor," aka TA, aka the person who'll most likely be grading your papers and leading your sections. By the time you graduate, you will know at least one person who sleeps with his or her GSI.
Hate Man: A longtime fixture in People's Park, Hate Man, or "Hate," is actually a former New York Times reporter who developed a life view of "oppositionality." He may greet you with "fuck you" (but in a loving way) and can often be seen pushing other homeless folks as a barter method for cigarettes or coffee.
hella: Bay Area slang for "a lot of."
I-House: aka International House, this is a dorm/community center for international students, as well as one of the best-kept dining secrets on Southside.
Indian Rock: A large rock outcropping/park on the west side of Indian Rock Avenue in the North Berkeley Hills that has an excellent, unobstructed view of the bay and San Francisco. Before dark, you'll see a lot of local kids climbing on it; after dark, it's an absolutely foolproof place to bring a spliff, a bottle of wine, and/or a date. Just don't fall off.
KALX: Cal's mostly-student-run radio station (and also one of the best in the East Bay), residing at 90.7 FM. Singlehandedly responsible for keeping obscure Moroccan techno from the Eighties alive and well.
KPFA: A progressive, non-commercial, listener-supported radio station (94.1 FM) spawned from the Pacifica Radio network. Home of several well-reputed news and music programs. Constantly mired in labor disputes. Known for petitioning, protesting, and occasionally suing itself.
Northside: The neighborhood just to the north of campus, clustered roughly around Hearst Ave. and Euclid St. Cuter, quieter, and a bit more low-key than Southside.
Oski: The official name of UC Berkeley's mascot. Now you know.
People's Park: Located between Haste Street and Dwight Way near Telegraph Avenue, People's Park is UC Berkeley property that was turned into a public park in 1969 by some of the same people involved in the Free Speech Movement. Although still a potent symbol of the turbulent Sixties, People's Park today is known more for its homeless population.
Pink Man: A guy who rides around Berkeley on a unicycle in a pink bodysuit. Yep, we're serious.
Southside: The cluster of shops, bars, restaurants, and housing that lies south of Bancroft.
The Bay: Not to be confused with the body of water called San Francisco Bay (fun fact: actually an estuary!), "The Bay" is common parlance for the Bay Area.
The Big C: Pretty much exactly what it sounds like — a really, really big concrete block in the shape of the letter C, built into one of the hills overlooking campus.
The Big Game: Cal's annual football game against Stanford and the annual expression of one of the longest-running rivalries in college football. In the week leading up to it (if it's the year Berkeley hosts), campus typically holds a massive bonfire at the Greek Theatre (though this year's version is sadly canceled due to scheduling conflicts).
The City: What locals call San Francisco.
The Glade: Officially Memorial Glade, this big ol' patch of grass is a great place to study, sit or play Frisbee. It will be responsible for whatever modicum of a tan you'll get living in Berkeley.
The Town: What locals call Oakland.
Tightwad Hill: A favorite of penny-pinching Cal football fans since basically the dawn of time, Tightwad Hill offers a mostly unobstructed view of — and an infinitely more liberal booze policy than — Memorial Stadium. It's located right off Stadium Rim Way on the northeast side of campus and is a bit of a steep climb, so wear good shoes.
Tilden Park: Huge, awesome park in the Berkeley Hills. Contains Lake Anza, a miniature steam train, a golf course, an old-fashioned merry-go-round, and lots of hiking trails and picnic areas.
West Bay: An East-Bay-centric term for San Francisco.
yarn-bombing: The very Berkeley practice of knitting colorful sleeves around street signs, parking meters, and the like as a sort of public art project; also an excellent thing to point out to your visiting friends and family as evidence of how totally wacky! this city is.
Zachary Running Wolf: If there's a protest, he'll be there. Currently running for mayor of Berkeley. Big fan of sage.