Today Years Old on Instagram: "Today isn’t just October 3, it’s Mean Girls Day. The date comes from a scene in the 2004 comedy Mean Girls when Cady Heron (Lindsay Lohan) tells her crush Aaron Samuels (Jonathan Bennett), “It’s October 3rd.” Written by Tina Fey and directed by Mark Waters, the cult classic is known for its sharp humor, iconic lines like “On Wednesdays we wear pink” and “You can’t sit with us,” and its satire of high school cliques. Each year, fans mark October 3rd by sharing memes