Mike D (of the Beastie Boys) - Mike Rhymes the Same Word Twice
Mike says the following line: "Everybody's rapping it's a commercial / thinking that life's just a big commercial". The second "commercial" was actually supposed to be the word "rehearsal". When the other Beasties quickly realized what he had said, they would not let him redo the take and forced him to accept his mistake on the single and album.
the song "Pass The Mic" from the album "Check Your Head"