Freeganism

Freeganism is the practice of eating food for free whenever possible. It should not be confused with Reaganism, which is the practice of eating other people's food for free whenever possible. Freeganism is generally expressed through taking perfectly good food discarded by stores and restaurants and eating it. More pithily, freeganism is a fancy word for eating out of the dumpster.

Rationale
The movement generally points out that if not for them, most of the food would just go to waste. Because it's "waste," this apparently absolves all freegans from any guilt regarding whatever went into producing it in the first place, whether animal slaughter or slave labour. The movement is largely made up of "lifestyle" anarchists, who also use it as a way of cutting into the profits of capitalists. They also generally don't take work in corporations, preferring volunteer work or just not taking a job, and refuse to be exploited to survive.

An important part of the movement is that many members are either completely vegan, or refuse to have meat unless it is free, as anything else is rewarding businesses for eco-unfriendly practices.

Motto
The unofficial motto of the movement is "There IS such a thing as a free lunch."

Critiques
Ewww. Just ewww. That being said, ickiness and health dangers will vary widely between dumpsters. Most of the food is wrapped in some kind of packaging and stored in somewhat sealed plastic bags. It just resides in a different box than it used to.

However...
The main argument freegans make in regards to people wasting good food is sound. There is a very big issue with people wasting edible food especially in developed countries like the countries of Europe and North America. It's a problem that should be addressed with good solutions. Encouraging people to rely on dumpster diving as a cheap first resort to getting free meals is not one of them.

As distinct from
Freeganism should not be confused with the practice of graduate students attempting to freeload food and drinks from departmental seminars and open days, nor with art students learning to subsist entirely on rubber cheese and gasoline-flavored wine from exhibition openings. Those are just prudent good sense.