W32/Crog.worm
W32/Crog.worm is a worm (computer virus) which spread via MSN Instant Messenger and peer-to-peer file sharing networks circa March 7, 2005. Its name is a contraction of Crazy Frog. Its goal is to weaken a computer's security, but not to cause any real damage. Not much information is available about this virus, apart from an archived McAFee report on it. No binaries seem to exist presently.
The name stems from two files the worm copies to the root of the infected computer's file system: Crazy frog gets killed by train!.pif and Annoying crazy frog getting killed.pif. The actual executable was not named after Crazy Frog, but rather, disguised as an MSN updater.
Somewhat notably, the worm opens a web page on the user's web browser, listed as http://frog.0catch.com/(blocked)big_deal.jpg. This could possibly be the origin of the "What's the big deal?" image. The image appears to be dated 2005 on the bottom-right corner. The artist is still unknown.