I chose the word because it's inoffensive and has a really long replacement.
If you slap some tags at the end of a post, then post a lot of swear words that will be replaced by longer words by the filters, and put the tags at the end (just so it will be parsed correctly), mySQL will truncate the post (which will now be longer than the allowed limit) and the tags will be unclosed.
Someone with an account at Invision could try to link to my above message at their bug report forums. Accounts are free but I can't be bothered. Who knows, maybe we'll get a free something or other.