Males and females of several monkey species urinate into their hands and then vigorously rub the fluid into their fur.  Historically, scientists have posed various theories to explain this behavior, ranging from regulating body temperature to communicating aggression.  Now, brain images of female capuchin monkeys have revealed that male urine sends sexual signals.

Read about it here:  http://news.nationalgeographic.com/news/2011/03/110302-monkeys-wash-urine-attractive-mates-animals-science/