What does it take to be a real cowgirl? A whole lot more than a pair of shiny guns, according to Book-Its latest adaptation, as the audience hitchhikes down the life road of Sissy Hankshaw and her enormous thumbs, the catalyst for a story that is entertaining and surprisingly thought-provoking. A special tip of the hat to the productions sound design and music; the guitar-strummin cowgirl and her fiddle-playin sidekick act as musical narrators and seamlessly move the story forward. Kudos to every cast member (it takes a lot of courage to be that naked on stage), but especially to Hillary Pickles as Bonanza Jellybean, who brings the character an honest child-like openness, thrusting not just her breasts forward but her heart as well. Despite the storys inherent silliness, its rooted, touchingly, in the beginnings of the feminist movement. Book-It says they want to inspire audiences to read, and indeed after seeing Cowgirls, I cant wait to get my hands on a copy. DYLAN SLADKY 7:30 p.m. Wed.-Sun. plus some 2 p.m. Sat.-Sun. matinees. Ends Oct. 12.