Improvisation

The Wikipedia has all sorts of amusements:

[Robert] Plant, known generally for his improvisation while performing live, would ad lib during live performances of "Kashmir". He would add in "sweet mama", "slowly dyin'", "now just a minute", "sweet darlin'", and he would stutter the words "baby" and "mama". He would also end that section with "there's no denyin'" and "Woman, talkin' to ya!"