From Compsci.ca Wiki
Mazer's avatars are often a Ninja'd version of something in the theme, while Cervantes' avatars are always Pirated (oh, oh, pun!).
Turns out alot of people type "Pythong" when they mean to type "Python" and somebody decided to take advantage of it.
What the Duck?
The biggest, avatar theme was DuckFest.
The Baldur's Gate Revolution
In December 2005, Cervantes and Mazer made Chuck Norris avatars.
Penny Arcade Violence
In January 2006, Cervantes and Mazer made avatars involving violence in Penny Arcade.
Calvin and Hobbes
In February 2006, Hikaru79, Mazer, and Cervantes made avatars of Calvin and Hobbes. Hikaru79 had a Calvin and Hobbes avatar for a long time, and had promised to partake in some of the previous avatar themes, though he never did. So, Cervantes and Mazer brought this month's avatar theme to Hikaru79.
March 2006's avatar theme was actors or characters from movies.
To go along with the April Fools joke of 2006, some users (without their consent) changed their avatars to a Hello Kitty theme.
Aside from the one day Hello Kitty event, April 2006's avatar theme was Bill Gates, since he is so loved by everyone in the CompSci.ca community. This was Mazer's and Cervantes' April Fool's joke extended for one month. As a further joke, they switched the ninja/pirate rule: Cervantes used a ninja avatar made by Mazer while Mazer used a pirate avatar made by Cervantes.