Swearing is part of programming and trying to remove it is outright silly… that said, deviantart found out the hard way that an overzealous filters will break their site.
“I just wanted to let you know that the reason why deviantART’s CSS isn’t loading properly for some people is because one of your CSS files has f*** in a stylesheet comment.” - deviantart.com
Let that be a lesson, front end developers don’t get to swear, but the PHP/ASP/Python/SQL back end guys? Swear on….