wget -O mybb.zip http://www.mybb.com/download/latest
unzip mybb.zip

root@lampwebserver:~/temp# unzip mybb.zip
Archive:  mybb.zip
  End-of-central-directory signature not found.  Either this file is not
  a zipfile, or it constitutes one disk of a multi-part archive.  In the
  latter case the central directory and zipfile comment will be found on
  the last disk(s) of this archive.
unzip:  cannot find zipfile directory in one of mybb.zip or
        mybb.zip.zip, and cannot find mybb.zip.ZIP, period.