If there's one thing Techers like, it's free food. Unfortunately, this is hard to come by -- unless you know your way around campus. Which is why I present this informative guide to hunting and gathering, scrounging, and (cheaply) buying food at Caltech.
Hunting and Gathering
You, too, can benefit from this ancient technique, developed by those of your ancestors to lazy to farm for themselves. It's main advantage at Caltech is that it's the easiest way to get food on campus after 2 AM (in fact, that's the only time I recommend using it). The drawback is that only a small selection of foods is available during any given season, thanks to Caltech's policy of planting primarily decorative, and not edible, plants.
Oranges are one of the most plentiful foods on campus, ripe during the winter. Don't be fooled by the bounty on the Orange Walk -- most of those are sour and suitable only for funnelating/potato gunning. There are a few good orange trees, though -- a little experimentation should lead you to the sweet ones. All of the orange trees in the Fleming courtyard, likewise, are good to eat, but don't let them catch you stealing them. Beckman Institute also houses some orange trees. It's a long walk, but those juicy blood oranges are worth it.
Grapefruit are also available on the Orange Walk. They're great when ripe, also during the winter months.
Squirrels are (reportedly) edible, although I don't know of any students who catch them to add them to their diet. Squirrel traps aren't hard to make; check an old Boyscout handbook or outdoors skills guide. Just be careful not to catch the campus cats by mistake (I know what you're thinking, but don't try it -- but they taste bad and their owners will likely object) and remember to cook the squirrel meat thoroughly -- they're probably diseased.
Speaking of diseased, the Throop crawfish look delicious, but you can't help wondering what chemicals have been dumped in their pond. My plan, if I ever get time, is to capture two crawfish and breed them in a separate, clean container. Their offspring should be perfectly healthy, and make an excellent weekend meal.
Same goes for the Baxter Pond frogs.
Scrounging
This is the ultimate food source for lazy college types. A clever scrounger can live quite well off campus leftovers, probably better than off a board diet. Here are the best places and times to scrounge on campus.
Your own Hovse: Scrounging starts at home. Poke around the "public" shelves in your Hovse kitchen. Baking soda + 4-year-old frosting + gross candy from last Halloween = good meal. Sometimes you can also find leftovers from parties or people's failed cooking experiments. There may also be other sources of food around, depending upon your particular Hovse. As far as Blacker goes, I recommend the Tunnel candy dishes.
SAC courtyard, Friday at 8 AM: ASCIT donuts. Techincally, these aren't totally free because you paid ASCIT dues to get them, but they are free after you eat the first $20 worth. Get there promptly because they do move fast.
SAC: Drug and Alcohol Counsellor's office: I've never checked, but it's supposed to have refreshments. Most of the counselling offices down there supposedly do. You might have to come up with deeper problems than just simple hunger to justify eating all their candy, though.
Sloan 355, weekday late afternoons: Afternoon meetings in this room sometimes leave tasty leftovers. While I have never been able to time this one correctly, I frequently see the empty dessert platter on the back table.
Registrar's office: A good source of candy and cookies. Be sure to bring along some random question about your schedule to keep them busy while you munch the food.
Steele main entrance, weekdays 4 or 5: If you're there right after a conference, the clean-up people will let you have left-over snadwiches, candy, and sodas.
Steele House: Another good source of candy -- but again, be sure to come up with some random questions about Caltech to justify your visit.
Buying Food
If you have a little cash, you may want to resort to actually buying your own food. If you have no car and are unwilling to walk long distances in the dark, your only option is on-campus food vendors. These come in two varities.
Stores/Cafes: Your best bet among these is the C-Store, which is open until midnight and has the largest food variety. The Red Door Cafe is not a good choice unless you're a morning person and like Starbucks-ish fare. The Coffeehouse, located in the SAC, is the only food vendor open until 2 AM and has a nice selection of food and drinks. If you're a EE, the EE stockroom in the subbasement of Moore sells cheap vending-machine-type food, but it closes before 5 PM.
Vending machines: They're always open, always cheap. A diet of candy bars and chips does get old after a few days, though. Here's a complete-to-the-best-of-my-knowledge guide to vending machines on campus: