ad-lib caught napping caught off balance caught short extemporaneous extemporized haphazard hasty impromptu improvised makeshift precipitate rough-and-ready snap surprised taken aback taken by surprise taken unawares tripped up unarranged unbegun unconcocted uncontrived undeliberated undevised unmade unmanufactured unorganized unplanned unpremeditated unprepared unprimed unready unstudied