An MP3 file designed to aggravate music swapping users and help deter illegal copying. Cuckoo eggs are either erroneously named or edited. For example, a song with a heavy metal title is really elevator music, or, after a few seconds of the original music, random noise, speech or even cuckoo clock sounds are heard until the end of the file.

The first cuckoo egg was released by Michael and Stephanie Fix in 2000. The idea was that eggs would be quickly propagated throughout file swapping services because titles are often not listened to before being made available to others. The term comes from the cuckoo bird, which lays its eggs in the nests of other birds. For more information, visit www.hand-2-mouth.com/cuckooegg. See Easter Egg.