To write positive things about people with your own first name on urban dictionary. In most, however not all, cases a way of making up for personal insecurities.
A less popular form of Katieing is to write opinions about other people you know.
Whether or not the statements written about the concerning person are true or not, is irrelevant.
Jimmy: Simon has been Katieing like crazy man, he writes he has a huge c*ck!