I guess you all heard about Saatchi & Saatchi London being fired by Dr Martens for running an advertising campaign featuring dead rock stars Kurt Cobain, Sid Vicious, Joey Ramone, and Joe Strummer wearing the their Doc Martens boots in heaven. The distribution of the ads had not been authorized by the brand and therefore they appeared "illegaly" on some magazine causing a lot of buzz and the eventual discharge of the agency.
Well, if you're interested in discovering similar "unauthorized" ads, or in spoofs of popular campaigns, you can have a look at illegaladvertising.com. The site features a rich collection of ads you were not supposed to see. Of course, if you feel "illegal" and brave enough, you can also submit the great ads you created but your client never signed-off...