impertinent, irreverent, pert, saucy -- (characterized by a lightly pert and exuberant quality; "a certain irreverent gaiety and ease of manner")
fresh, impertinent, impudent, overbold, smart, saucy, sassy, wise -- (improperly forward or bold; "don't be fresh with me"; "impertinent of a child to lecture a grownup"; "an impudent boy given to insulting strangers"; "Don't get wise with me!")