Ride 'Em, Cowboy

Japanese monkeys - just like people:

Japanese macaques are known to ride deer like humans ride horses, for fun or transportation — behavior the deer seem to tolerate in exchange for grooming and discarded food. But these monkeys were up to something different.

The researchers compared the monkey-deer interactions, which happened during mating season, with homosexual monkey-monkey interactions, where female macaques mount each other. They paid close attention to the "mounting postures" the monkeys assumed on the deer, and the vocalizations they made, to determine that the interactions were, in fact, sexual ... at least for the monkeys.