vivacious
as Francine Frank and Frank Anshen point out (Language and the Sexes), both girls and boys may have lively personalities, but when did you ever meet a "vivacious" boy? Two-thirds of the American Heritage Book of English Usage's panel on usage felt that "vivacious" could be used only of a female subject. You could either begin describing appropriate men as vivacious or use more inclusive substitutes: spirited, high-spirited, full of pep, breezy, animated.
