Polly want a cracker (AmE) or “Polly wants a cracker” (BrE) is a cliché phrase taught or said to parrots and other birds with speech-mimicking abilities.
According to Urban Dictionary, it is also said when a black woman is fond of a white man, as among African Americans the word “cracker” is a term used to refer to any European or European American.
The expression is believed to be made up by pirates, maybe because it popped up in Robert Louise Stevenson’s world-famous novel Treasure Island (1883).
However, the first written record of Polly referring to a female parrot comes from Ben Jonson’s Epigrams (1616).
According to OED Polly is the diminutive form of Poll that is a female name or the name of a parrot.
“Polly wants a cracker” was first used in a cartoon in 1848 in a satirical magazine named The John Donkey.
The word “cracker” was a pun in the magazine referring to the biscuit as well as the boy in the cartoon who is ready to crack the parrot.
Later, in 1876 Nabisco (National Biscuit Company) choose the phrase to be their slogan which became extremely popular.
Since Nabisco has used “Polly want a cracker?” for their slogan, the term has become part of the common language and appeared in pretty much every movie with a parrot in it.
Just to mention some: Perry Mason: The Case of The Perjured Parrot (1957), The Brady Brunch (1967), Aladdin (1992) or Scary Movie 2 (2001).
Also, in some movies, alterations refer to the original phrase, like in the Simpsons, Mr. Burns asking “Smithers want a cracker” (1989) or in Batman and Robin (1997) where Poison Ivy asks Robin “ Polly want a Kiss?”.
Both examples express oppression, similarly to how the world-famous rock band Nirvana used the term in their song Polly (1991).