I found out this week that the group who decides by discussion and vote which words are so offensive in themselves that they are not allowed in play in Scrabble or Words with Friends publishes a list of all such banned words. However, in order to avoid becoming the target of search engines looking for those words, they list the words with the letters in alphabetical order (unless the letters of the word are already in alphabetical order, in which case they spell them backwards). For those looking for unique new insults to throw out when they have run ou of logical arguments, the list is included here --
scrabbleplayers.org