Mean Girls character Janis Ian was actually inspired by very famous celebrity

Not to make you feel old or anything, but despite Mean Girls coming out in (gasp) 2004, we're still finding out new things about the plot twenty years later.

Not only has it been two decades, it's also 3 October today, and who on earth could ever forget Lindsay Lohan's iconic delivery of "It's October 3rd" in the best movie to ever exist? Certainly not me.

So let's get into everything Mean Girls.

The creator of the iconic high school film, Tina Fey, has revealed that one of the main characters was based on an American icon.

In Mean Girls, Janis Ian (Lizzy Caplan) is an angsty student who yearns to get revenge on her ex-best friend, Regina George (Rachel McAdams).

Characterised by her grungy style, it turns out Fey took inspiration from one very familiar, punky face.

It was in fact Kelly Osbourne, which makes a lot of sense if you think about it.

But that's not the only bit of mind-boggling Mean Girls information out there that revolves around Regina and Janis.

It turns out it took some fans 20 years to understand one pivotal punchline.

In the film, Regina says: "Let me tell you something about Janis Ian.

"We were best friends in middle school."

Regina then says Janis was 'jealous' of her boyfriend and totally 'obsessed' with her.

Sure, Regina.

She continues: "So then for my birthday party, which was an all-girls pool party, I was like 'Janis I can't invite you because I think you're a lesbian'."

Janis Ian was based on a rockstar's daughter (Paramount Pictures)

Regina then concluded: "I mean, I couldn't have a lesbian at my party!"

While rewatching the film, it clicked for many that perhaps it was poking fun at Regina's intelligence - as it's revealed in the final scenes that Janis is of Lebanese descent.

The implication being that Janis told her bestie she was Lebanese - not a lesbian - and it was just too much for the queen bee's brain to handle.

Very clever from writer Fey.

One person wrote on social media once making the connection: "My dumba** just realised in Mean Girls everyone thought Janice Ian was a lesbian because they misheard her say she’s Lebanese and that’s the joke."

Another added: "It took me nearly 20 years, but I finally made the connection of the Janice Ian Lesbian/Lebanese joke in Mean Girls. Thanks."

A third added: "Earlier in the movie Regina says she stopped hanging out with Janice cos she’s lesbian. So the entirety of mean girls happened cos Regina didn’t know the difference between lesbian and Lebanese."

The more you know, eh?