The internet filtering we experience here is sometimes odd and unpredictable. There are two primary filtering mechanisms: a "blacklist" of specifically prohibited sites (such as www.youtube.com, *.blogspot.com, *.wordpress.com, etc); and a "URL filter" - any web address that contains a prohibited term, such as (for the sake of illustration) "pen". The party in charge doesn't make either of their lists public, and both lists are subject to unannounced change. One recent change, for example, was the addition of *.blogspot.com to the blacklist.
From what I can tell, the affect of trying to visit site on the "blacklist" results in nothing more than the site failing to load.The effect of trying to visit a web address that contains a prohibited term, though, is that your internet access is suspended for one or two minutes. You can tell which filter you've run into by the affect it has on your browsing experience.
That's the background for this afternoon's google search.
When you type a term into the google search box and hit enter, google loads the "search results" page- which contains in its address the term searched for. The search results page (and www.google.com) is not on the "blacklist," but because of the way Google dynamically generates search results, any terms you search for will still be subject to the URL filter. Consequently, you can occasionally discern what hot-button terms you're not allowed to google for.
Today's secret word is "triangle."