Interesting that the supreme court ruled on this specifically
> The California Supreme Court also decided that the act outlaws sex-based prices at bars (ladies' nights): offering women a discount on drinks, but not offering the same discount to males. In Koire v Metro Car Wash (1985) 40 Cal 3d 24, 219 Cal Rptr 133, the court held that such discounts constituted sex stereotyping prohibited by this Act.