When some random person, possibly from the Urban Dictionary editor's room itself, targets certain authors and thumbs down all of his/her definitions when there is nothing wrong with them. Usually these kind of people have no lives and just thumbs down people’s hard work every 6 hours or so. I myself am a victim of Set Targeting. I’ve created more than one pseudonym and many of them have been targeted. The only logical solution that comes to mind is that somebody within the editor’s room notices familiar pseudonyms and thus targets them every day for his own personal amusement.
The best way to prevent set targeting is to simply space your definitions out under many different names and do not group them all under one pseudonym. If you only make one word per every pseudonym instead of grouping several words together into a set, then it makes the definitions less vulnerable for targeting.