A new virus called “Is This Your Mom” seems to be plaguing Facebook users now. What basically happens is when you are logged into your Facebook account, you start getting Facebook chat popups from your friends with a chat that says: is this your mom? http://apps.facebook.com/videomedianow/
It links to a spam application, which on opening asks your Facebook user email and password. You should know that for adding any Facebook application to your account you need not give your username or password separately but you just have to give the required permissions. Here is a screenshot:
