Today I learned that "cynic" derives from the Greek word κυνικός, kynikos, "dog-like". It's origins lay in the ancient Greek philosophical school of Cynicism. The philosophy is critical of human society, viewing social conventions and material things with indifference, or even disdain as pretentious and inevitably corrupting influences to be disillusioned with and broken away from. Cynics seek a more honest and free way of living that is meant to ultimately bring you and others greater satisfaction. Early cynics were viewed as so crude that they were mocked as living like dogs, particularly Diogenes whose slept on the street inside of a giant wine jar, and was so candid that he ate, made love and even used the bathroom right there in public, and didn't care what anyone thought. He embraced the insult that his behavior was like an animal, and is claimed to have said, "other dogs bite their enemies, I bite my friends to save them."
There is much we can learn from dogs. Dogs are honest, they express themselves naturally as they move through the world. There's no hypocrisy or deceit, they are what they are. They are also faithful animals that defend those they love and also aren't afraid to warn you of unpleasant truths. They're brave actually. Usually dogs are also good judges of character, and know what's what. Cynics have historically been likened to watch dogs of their philosophical tennets. Sometimes their bark or bite is nasty, but that doesn't mean they are not helpful.
Something else Diogenes is supposed to have famously said is, "I fawn on those who give me anything, I yelp at those who refuse, and I set my teeth in rascals."
Note that when Diogenes says "those who give me anything" he is really talking about someone who can teach him anything, not the finer things.
In fact Alexander the Great went to meet him, and offered to grant him anything he wished, Diogenes, who was relaxing out in the sunlight motioned the king way and retorted that what he could do for him was, "Stand aside to stop blocking the sun."
Legend has it that once an Athenian was leaving a food offering to the Gods, and a white dog took the meat from him, and ran off. The man chased the dog, who dropped the dish outside the gates of Athens and fled. A temple to Heracles was later said to be built on the spot where the food fell. It was called the Cynosarges, or "White Dog". Later a gymnasium was built there and this is where Antisthenes, the founder of Cynicism, taught others. He was referred to as "The Absolute Dog"