"Mother-in-Law" is a 1961 song recorded by Ernie K-Doe. It song was a number-one hit in the U.S. on both the Billboard Hot 100 and R&B charts. The song was written and produced by Allen Toussaint who also played the piano solo. It was issued by Minit Records. After several unsuccessful takes, Allen Toussaint balled the composition up and threw it away as he was leaving the room. One of the backup singers, Willie Hopper, thought that it was such a good song that he convinced Ernie K-Doe to calm down and give it one more try.