Cold sores are nothing to be ashamed of. They affect almost everyone. Even celebrities. Yes, poor Katie Holmes, Alexa Chung, Rihanna and even Angelina Jolie have all been papped sporting the suckers. But although most people know the basics — as in sharing a toothbrush or glass with someone who has a cold sore is a no no, as is pashing them, sorry! — a quick survey of the office revealed that people don't tend to know the ins and outs of the virus, such as the medical term, what causes them and how best to treat them. So we thought we'd test your knowledge to see just how much you know about cold sores now!