Give this a try, let me know what you get.
First, let's search Baidu, one of the major chinese search engines, for "chocolate".
Ok now let's try... "Tianamen massacre", written in western script.
Ok now try this.
Woops! You'll likely get a web-browser generated error message saying something like "Connection interrupted" or some such.
Hit your browser's back button and reload that chocolate query. Doesn't work either does it?
Bravo. You've just been temporarily blacklisted by the Great Chinese Internet Censorship Program for searching for politically subversive terms ("Tianamen massacre" in chinese).