Peanut Gallery Meaning

(idiomatic) Any source of heckling, unwelcome commentary or criticism, especially from a know-it-all or of an inexpert nature. May also now refer to general audience response: "Let's hear it from the peanut gallery."

Example: 2001: John E. Kleber, The Encyclopedia of Louisville, page 630 (University Press of Kentucky; ISBN 9780813121000)
  As early as the 1870s, most theaters allowed African Americans to sit in designated areas, while the dress and parquet circles were reserved for whites. A few theaters did not allow blacks at all. In the early 1920s, black leaders protested these “peanut galleries” on the grounds that African Americans paid the same ticket price. A boycott was organized that resulted not only in the closing of the peanut galleries but also closing of the theaters to blacks altogether. It was not until the public accommodations drive in the early 1960s that all theaters were opened to blacks. On May 14, 1963, the Louisville Board of Aldermen passed the public accommodations law that made discrimination in all public facilities illegal.
  Enough already from the peanut gallery; if you think you can do a better job, go right ahead.