Um... custom titles? Like my silly "Fish out of Water" phrase?
If that's what you mean, they're given out as rewards--usually for a long history of good behavior of contributive members.
Or people who sleep with those of high authority. Worked for me and Hobo anyway. I wouldn't suggest it to anyone else though.
EDIT: Again, if I interpretted what you meant correctly and you did mean CTs, then just remember that most questions like that are answered in the FAQ section. We get this question all the time.