I don't know but there is a spotty nerd called Liam crumlish from barnfield south academy
Chat with our AI personalities
Nothing happens other than getting the achievements and trophies in modern warfare 2. But in modern warfare 1, you get to unlock certain cheat codes that can be used during the game.
You can obtain new titles and emblems but that is all, everything else such as weapons and challenges are reset.
Challenge: "Free-for-all Victor: I" - Place first, second or third in 3 Free-for-all matches. http://callofduty.wikia.com/wiki/Callsigns For all Titles and Emblems.
You unlock the museum, an extra level displaying all of the levels off the campaign.
Call of Duty World at War, Modern Warfare, Modern Warfare 2, Black Ops, and Modern Warfare 3 all have online multiplayer.