I think you are refuring to the counter file sharing tactics that are and have been used by oragisations like the RIAA. That involve offering bogus files for download via p2p networks. The idea behind this, from what i have read, is to frustrate peoples attempts to download copyright matterial.

The idea being an agent provocatuer offers a file for download. That file will be advertised as an atractive piece of copyrighted matterial. The latest chart hit or movie etc. The p2p user downloads this file and shares the file with many other users of the p2p network. The file however is bogus. Some examples friends of mine have downloaded; are music files that play a small clip of the music with a message that they are involved in an ilegal activity and directs them to a place where they can obtain a legal copy.

The reasoning behind this is that if enough people can be frustrated using this techneque. They will give up on the p2p networks. I no for certain that this has been somewhat successful, at least two of my friends that used to dowload music have given up in frustration.