I think you're looking for this Mod by Calorie:
Allow Users to Self Censor Words
The problem is though (although, it MAY NOT be a problem) is that there is no confirmation of this Mod working on anything more than vB 3.5.x. I'm still looking at the Mod to see if anything can be done to make it work with more recent versions of vB, but I ain't no coder.!
Hope it helps a bit....
PS. please let me know if you, or someone happens to get the Self Censor Words Mod to work with 3.6.x. Thanks.