"Deko" in Japanese is short for "decoration" and "chari" is slang for "bike".
The dekochari was a response by children to the Dekotora ("tora" is short for "truck") craze which swept Japan after a series of movies called Truck Yaro was released.
These movies featured giant trucks decked out in chrome and flashy lights.
Unable to drive the giant chrome-plated flashing trucks they coveted, children instead built plywood boxes around their bikes and attached chrome plating and lights.
Almost all current Dekocharis have elaborate light displays and many include hi-fi audio systems and cup-holders.