That sounds unwieldy. Sex with sheep is a much more popular choice, at least according to one study published in the Journal of Sexual Medicine. During the research, led by urologist Stenio de Cassio Zequi, 492 men from rural Brazil were examined. The men participating ranged in age from 18 to 80. 118 of these men had been diagnosed with penile cancer. 45 percent of the group that suffered from penile cancer had sexual relations with animals, compared to 32 percent of the healthy males. Of those men who had sexual relations with animals, 59 percent reported having sex with animals for one to five years and 21 percent had been doing it for more than five years. Sexual interaction occurred as often as daily and included animals such as horses, cows, pigs and chickens. Researchers believe that sexual interaction between humans and animals may produce micro-traumas in the penis such as scratches and cuts. They theorize that animal secretions may be toxic to humans and that some unrecognized microorganism may be responsible.