found this list of top 10 callsigns for modern warfare 2. Some of these seem impossible.
http://www.wrixel.com/2010/01/modern-warfare-2s-top-10-hardest-callsigns/
http://www.wrixel.com/2010/01/modern-warfare-2s-top-10-hardest-callsigns/
http://www.wrixel.com/2010/01/modern-warfare-2s-top-10-hardest-callsigns/
http://www.wrixel.com/2010/01/modern-warfare-2s-top-10-hardest-callsigns/