Have you ever read an Asterix book?
Asterix (or the authors thereof) extends this usage with little pictograms of skulls, thunderclouds, shaking fists etc. and is a classic example of how something potentially offensive can be expressed in a comical manner.(Standardized Curse Symbols)
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I was considering the possibility of adding a CWBUM tag such as [expletive] (or more likely [fuck], [shit], [piss], etc) which could be replaced on the fly by an appropriate UniCode string of characters. You'd still get all the satisfaction of typing the word 'fuck' (and so on), but it'd be rendered differently a la Asterix.