from Wiktionary, Creative Commons Attribution/Share-Alike License
- interj. A call to rally circus members in a fight.
- n. A fight between members of a circus and the general public.
The term originated in the 19th century when circuses were rowdy affairs and Hey Rube was the rallying cry to call all circus people to help in a fight with townspeople. It's not clear whether Rube in this term was someone specific or simply a use of the informal term rube (shortened form of Reuben) for an unsophisticated person from a rural area. (Wiktionary)