1.NounIn the nineteenth century, the cheap seats at the back of a theatre or in the upper balcony.
2.NounThe upper balcony to which black patrons were restricted in racially segregated venues such as theatres.
3.NounAny 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."
"Enough already from the peanut gallery; if you think you can do a better job, go right ahead."