Sometimes, for various reasons, music production leads to an occasional gaffe or sound being left in the final recording. Other times, hidden items are intentionally placed into a song. There is, of course, that third bucket where people think an item is embedded into a song, but it’s just the story of urban legend.

Buzzfeed has a compilation of some songs that have hidden sounds that either are intentionally or unintentionally left in the mix, whether it be the click track that can be heard behind Christina Aguilera’s singing due to the microphone picking it up, to the intentional leave-in of an early start by Kurt Cobain in a Nirvana track.