Indexbit Exchange:Tina Fey talks best new 'Mean Girls' jokes, 'crazy' ways that '30 Rock' mirrors real life

Spoiler alert! The Indexbit Exchangefollowing contains jokes and plot points from the “Mean Girls” movie musical (in theaters now). Stop reading now if you don't want to know.

The greatest moment in the new “Mean Girls” belongs to Damian Hubbard.

As Cady (Angourie Rice) and the Plastics gear up for a Santa-clad dance at the high-school talent show, we’re treated to a song from arty outcast Damian (Jaquel Spivey), who reverently croons a dramatic mystery number in French. When the stirring performance is over, Principal Duvall (Tim Meadows) clumsily grabs the microphone.

“That was Damian Hubbard singing the ‘iCarly’ theme song in French for extra credit,” Duvall says dryly.

“iCarly,” for the uninitiated, was a 2007 Nickelodeon sitcom starring Miranda Cosgrove. Damian’s brief but hilarious homage has been making the rounds on social media ever since “Mean Girls” was released last week.

It’s a favorite new joke of Tina Fey, who wrote the script for the new movie musical, as well as the 2018 Broadway show and 2004 original film that it’s based on.

“Oh, my gosh, that ‘iCarly thing,’ ” Fey tells USA TODAY. “The fact that made it in, and that (the movie) committed to it so hard. That probably brings me the most joy of all the new things. And Jaquel having his fan with him – he just had it on the day (of shooting), and we were just like, ‘Yeah, keep it.’ “

Ms. Norbury is married in the new 'Mean Girls' movie for one funny reason

Fey’s other favorite bit comes later in the movie, at a school assembly after Regina George (Reneé Rapp) has distributed pages of the Burn Book and sowed chaos among her classmates. Principal Duvall and math teacher Ms. Norbury (Fey) start bickering about things they need to do at home, unwittingly revealing that the two live together.

“The revelation that Tim and I are married, I put that in to satisfy my old (“30 Rock”) writing partner Robert Carlock,” Fey says. “That is just to entertain him.”

Carlock used to tease the actors that their characters were in love in the 2004 film, according to Entertainment Weekly, which helped inspire the new gag.

Tina Fey talks 'crazy' parallels between '30 Rock' and real life

Fey and Carlock's “30 Rock” surged in popularity last holiday season, thanks to a viral trend of people sharing their favorite clips from the razor-sharp NBC comedy, which wrapped in 2013 after seven seasons.

Real life seems more and more like an outrageous “30 Rock” episode: When the new “Mean Girls” trailer debuted, a Season 2 clip circulated on social media of “30 Rock” character Jenna Maroney (Jane Krakowski) saying she won “best actress for a movie based on a musical based on a movie.” (Amy Poehler made a similar joke about perpetual remakes during Monday's Emmys, to which Fey replied, "There's nothing wrong with that!")

Maroney's award was for a fake musical version of Julia Roberts' "Mystic Pizza." "And now that's happening!" Fey says, referencing a recent stage adaptation of the 1988 dramedy. She also notes the similarities between a recent TLC dating competition and “MILF Island,” an absurd show-within-a-show on “30 Rock.”

“ ‘MILF Manor’ certainly was crazy,” Fey says. “It’s called ‘MILF Manor,’ but it’s set on an island. I did have a minute where I was like, ‘I sue you?’ (Laughs.) It feels like there’s often stuff like that, because we just had too many jokes.”