They feel your pain
Some people can feel others' pain --literally. When those with a rare condition called mirror-touch synethesia see another person being touched or hurt, they actually feel the sensation themselves. There are several types of synesthesia, a neurological syndrome that causes senses to cross paths in the brain. For some synesthetes, for instance, specific colors create distinctive sounds in their head. Experts had heard only ancedotal accounts of mirror-touch synethesia until neuroscientist Sarah-Jayne Blakemore discussed the phenomenon at a seminar in 2003. "There was a woman in the audience who asked 'doesn't everyone experience that? Isn't that completely normal?" Blakemore tells Nature. Since then, Blakemore has studied 10 other mirror-touch synesthetes. All of them have overactive mirror neurons, which are the brain cells that allow us to see an action and comprehend it enough to be able to mimic it. "I have never been able to understand how people can enjoy looking at bloodthirsty films," says Alice, one of Blakemore's study subjects. "I can feel it."
(1) To some extent all of us do this. For example, one of my students tells me that once her boyfriend accidentally pulled her hair and yipped 'Ouch!' before she said anything. He claimed that it actually hurt him when he did it (I'm presuming that he doesn't have this condition).
(2) In general, I've always thought synesthesia is one of the coolest neurological conditions. A friend with perfect pitch tells me that he can tell if a note is off by its color --for example, A 440 seems red to him. That sounds very cool (though I'm not sure how much I'd like to have the version discussed here).