Erotic feet licking...

Foot fetishism is the most common body part related fetish. Researchers have hypothesized that foot fetishism increases as a response to epidemics of sexually transmitted diseases. Neurologist Vilayanur S. Ramachandran, currently the Director of the Center for Brain and Cognition, Professor in the Psychology Department and Neurosciences Program at the University of California, San Diego, and Adjunct Professor of Biology at the Salk Institute for Biological Studies, proposed that foot fetishism is caused by the feet and the genitals occupying adjacent areas of the somatosensory cortex, possibly entailing some neural crosstalk between the two.