Phantom Footgasms and the The Somatosensory Homunculus

In the case of some phantom foot patients, Ramachandran found that the amputees' brains didn't just fail to erase the missing foot from their body image map, they accidentally rewired the map in a way that caused the person's phantom foot to become sexy. Phantom foot patients reported feeling sexual pleasure, and even orgasms, in their missing feet.
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The Foot Fetish Brain Map
Sex nerd Emily Nagoski floats a possible explanation for the common foot fetish, and publishes an awesome diagram of the brain: "The somatosensory homunculus is the sensory map of your brain in your body," she writes. "You’ll notice that the feet are immediately adjacent to the genitals. So even though your feet are at one end of you actual body and your genitals are in the middle, as far as your brain is concerned, they’re right next to each other." And even if Nagoski is wrong, she notes that the somatosensory homunculus is "fun to say and makes you sound like a real smarty pants too."