Ah actually only a few strips had a black box, and that was because of a rather stupid thing I did concerning saving the strips to an uneditable format.
The swearing never use to be edited. However I recieved a few complaints that people couldn't share the strips with their elderly mothers. So I went back and changed most of them to the @)#($ style of cursing. However for a FEW I was unable to edit the text because I saved them improperly. So in came the "black box".
Perhaps I should make a poll. Black box the cursing or $)#*@ the cursing.