Capuchin monkeys are a small New World monkey species found in Central and South America. Female capuchin monkeys will sometimes indicate that they are ready to mate by throwing stones at males. They may also “flirt” by pouting, whining and shaking tree branches to attract attention. This aggressive behavior has probably evolved because capuchins, unlike most other primates, don't have visible physical signs of fertility and estrus.
Male capuchins will rub urine onto their fur in order to attract a mate. This trait is common in other New World monkey species as well and scientists believe that the smell indicates to females that a male is sexually mature.
More about capuchin monkeys: