In honor of Oct. 3, we've rounded up the 10 most valuable life lessons the girls and the too-gay-to-function Damian ("That's only OK when I say it!") of North Shore High have taught us!
1. Self Image-- Cady (Lohan): "Calling somebody else fat won't make you any skinnier. Calling someone stupid doesn't make you any smarter. And ruining Regina George's life definitely didn't make me any happier. All you can do in life is try to solve the problem in front of you."
2. Racism-- Karen (Amanda Seyfried): "So, if you're from Africa, why are you white?"
Gretchen (Lacey Chabert): "Oh my God, Karen, you can't just ask people why they're white."
3. Emotions-- Crying Girl: "I just have a lot of feelings."
4. Indifference-- Regina (Rachel McAdams): "Whatever. I'm getting cheese fries."
5. Privacy-- Janice (Lizzy Caplan): "That little one, that's Gretchen Weiners. Gretchen Weiners knows everybody's business. She knows everything about everyone."
Damian (Daniel Franzese): "That's why her hair is so big, it's full of secrets."
6. Endurance-- Regina: "Gretchen, stop trying to make 'Fetch' happen. It's not going to happen."
7. Halloween-- Cady: "In the real world, Halloween is when children dress up in costumes and beg for candy. In girl world, Halloween is the one night a year when a girl can dress like a total slut and no other girls can say anything about it."
-- Regina: "So then, for my birthday party
, which was an all-girls pool party, I was like, 'Janice, I can't invite you because I think you're a lesbian.' I mean, I couldn't have a lesbian at my party, there were going to be girls there in their bathing suits."
9. Trendsetting-- Bethany Byrd: "I saw Cady Heron wearing army pants and flip flops, so I bought army pants and flip flops."
10. Apologizing-- Jessica Lopez: "Laura, I don't hate you because you're fat, you're fat because I hate you."
This Oct. 3 also happens to be a Flashback Friday so here's ET's interview with Mean Girls
writer and Ms. Norbury, Tina Fey, back when the comedy first came out in 2004.