Motorcyle slang referring to a rider with a bike that is WAY beyond their capabilities. A metaphor between a rider so inexperienced atop a fast motorcycle and the Ewok piloting a Stortrooper speeder bike in Star Wars Episode VI: Return of the Jedi.
(verb) To ruin an otherwise excellent film by introducing a cheesy element which attempts to cater to the director's children. In all likelihood, however, they are probably embarrassed by it.
George Lucas totally ewoked The Phantom Menace with Anakin Skywalker's precocious one-liners.