Bloodhound Gang asked for permission to use a piece of music from an old '80s cure song, the permission was denied. so they changed one, maybe two notes, and used it anyway. it went on their first cd. They also noted all of it in the sleave of that cd, along with some choice words for the cure. pansy division rewrote the words to nirvanna's song "smells like teen spirit" and released it as a single, then later on a greatest hits collection called pile up. Then there's weird al yanchovik from the 80's & early 90's, (who mostly became a puppet for spoof songs, but started out on his own). It happens all the time.