Well, that proved it that it IS software strangely enough
Yes, the forums' "naughty words" filter is to blame. Occasionally, instead of just starring out words, the filter does a substitution (as Matt mentioned may be the case).
In this case, the filter automatically changes the 3-letter word that you used to "knocker". It is not pre-set in the software, I believe that it was changed by staff here a long time ago. IIRC, there was a complaint from one of our lady members (Princess maybe?) who did not like that 3-letter word and saw it as rude. We changed it in the filter as a joke and it's been that way ever since.
So, you were not the victim of some horrible word edit, just the victim of a really, really old joke.

Ok....and clearly the language filter is stuck to the on position in the new software.
For a while yes, but you should be able to turn the naughty words back on now...