because the encoded url is http://www.google.com/search?sourceid=chrome&ie=UTF-8&q=adult... and the HN code that truncates long urls chopped it in

because the encoded url is http://www.google.com/search?sourceid=chrome&ie=UTF-8&q=adult... and the HN code that truncates long urls chopped it in the middle of &#38 so it becomes "&#3" which is telling your browser to print the ascii character 3, which it can't show properly, so it shows the character you see instead.