We largely associate the circus with our more exotic animal friends: Elephants, tigers and even performing bears are what bring the crowds in. But you might be surprised to find out that our circus precursors — the Medieval or Renaissance fairs and carnivals that the circus slowly swallowed up by the 18th and 19th centuries — really often were dog and pony shows, where the easily available (and trainable) animals were taught to do tricks [source: Speaight].
But here's the thing: the dog and pony show didn't die when Big Circus showed up. In fact, these small "circuses" actually became a great way for somewhat disreputable folks to cash in on the lure of the Big Top without having much of an act. Often times, they were just little fronts for, say, bootlegging or a strip show that couldn't exactly be promoted, which is why they became strictly regulated in 19th or 20th century America [source: A Way With Words]. That's why the phrase "dog and pony show" is often used in a disparaging manner. We're just nodding to the hucksterism history of these off-brand circuses.