Sexist (3.5e Trait)
From D&D Wiki
Your character has something against the opposite sex and believes that the character's sex is the superior sex.
Benefit: Your character gains a +1 bonus on attack rolls against members of the opposite sex. He must be aware that they are the opposite sex for him to gain the bonus.
Drawback: Your character takes a -1 Penalty on attack rolls against members of the same sex. He must be aware that they are the same sex for him to take the penalty.
Special: This trait only works against humanoid looking creatures, such as mortals, and outsiders with a humanoid form. It does not work on monsters (a man doesn't get a bonus against a female centipede).
Roleplaying Ideas: Your character is constantly making remarks about the opposite sex. He might not necessarily be hostile, but he definitely has an apparent dislike towards the opposite sex.