MIA: He [Luke] would help people carry groceries home.
RORY: Oh, how very Boy Scout-y of you.
MIA: For a quarter a bag.
LORELAI: Oh, how very John Birch Society-y of you.
The John Birch Society is an ultraconservative, radical far-right political advocacy group. It was founded in 1958 by businessman Robert W. Welch Jnr (1899-1985), who saw it as a way to oppose Communism. Welch owned the Oxford Candy Company in Brooklyn, so maybe he was just on a major sugar high, but he denounced nearly everyone as a Communist agent, including former presidents Truman and Eisenhower.
The society is named in honour of Baptist missionary John Birch (1918-1945), a US military intelligence captain in China who was killed in a confrontation with Chinese Communist soldiers, ten days after the end of World War II. He was posthumously awarded the Army Distinguished Service Medal. Welch saw Birch as the first casualty of the Cold War.
The John Birch Society has had a resurgence with the election of Donald Trump, previously discussed, and its previously fringe views have now become mainstream in right-wing politics.