@osuccess, @ofail, and @odrop messages may contain %-substitutions, which evaluate to gender-specific pronouns if the player's sex is set. They are:
%a(absolute)Name's, his, hers, its
%s(subjective)Name, he, she, it
%o(objective)Name, him, her, it
%p(possessive)Name's, his, her, its
%r(reflexive)Name, himself, herself, itself
%n(player's name)Name
Capitalized pronouns are also available with %A, %S, %O, %P, and %R. If you need a '%', use %%.