www.alphadictionary.com

I know it's a reach, but is there a rational nexus between "rube" and "rhubarb"? The former is usually a term reserved for a hick or bumpkin; in the carnival world, "Hey, Rube!" was the coded cry for help from one carney to any other member of the carnival brotherhood, with imminent fisticuffs--usually with a greatly dissatisfied customer who felt he'd just been fleeced--being implied.

The latter--in addition to being one of two prime ingredients in a strawberry-rhubarb pie--can also refer to the sound of rampant flatulence, made with the tongue and lips, to indicate the ultimate in disrespect, mockery or derision.

Rube comes from the name Reuben, which was once used in the same manner we now use Rube.

Rhubarb turns out to be much more interesting. It's root means something along the lines of "foreign rhubarb." It was brought to Greece from an area along the Volga, called the Rha in Scythian. The -barb part is the same as in barbarian.

I believe rhubarb is also used to mean a ruckus such as often occurs in sports between teams and/or fans dissatisfied with a ref's call or something. In my head I relate it to baseball as often occurring after a pitcher hits the batter with a too close pitch. Accident or on purpose?

I noticed the baseball link, also. It appears to have come up out of nowhere in 1938 or so. No one really knows why.