A Sith Fair of Evilness was a fair, held by the Sith, that was infamous for being really EVIL. The fair was borne of a tradition that was begun in 4,000 BBY by Darth Malak, since he wanted to increase his credit with the Sith Order. Generally, all the things that all true Sith loved to do (though not, strictly speaking, the True Sith), such as planet destruction, gaining ultimate powah, killing people, etc. would be featured at these gatherings. Sith sign-up booths could also be found at the fair, and any young lad who had the dream of becoming a Sith Lord could join the Sith for a small fee of five bucks. The Sith usually held these fairs on a monthly basis, and they could take place anywhere across the galaxy.
Perhaps the least successful fair took place on Tatooine in 33 BBY. The failure was due not only to the location of the venue, but the fact that it was too early (because the Jedi wouldn't arrive until the following year) and the set-up crew was attacked by Sand People.