jpnyc would be the best person to answer this but I'll take a guess that it was a measure taken against spam. There are websites with that as part of the name and we may have been spammed by them.
I'm not aware of it being a bad word, so spam is the most likely cause of it being filtered.
If that is the case, it is due to a site which has that word separately as a prominent part of it's address (so it might be: *****.com , or: *****.tk, or: xyz.com/***** , etc). As to exactly which site, only JPnyc (or perhaps Brad) might know - but only if a log of that kind of thing has been kept.