I am itchy. You are itchy. We're all itchy together.

Some itches are caused by obvious physical triggers (OMG, there's a spider on your arm!). Others, though, have a more complicated source. Watching other people itch can make you feel itchy. In this piece at Scientific American blogs, Scicurious explains the neurobiology behind sympathetic itching. I got four paragraphs in before I had to scratch my neck. How about you?