A redneck joke is a joke about rednecks — working-class, rural or southern white Americans. For example,
A genie comes upon an African-American, a Jew and a redneck. He grants each a wish. The African-American wishes that his people be returned to Africa; the Jew that his people be returned to Israel. Once the redneck realises that all the blacks and Jews have left America, he wishes for a beer.