Get ready to go back to Genovia! From the iconic bleacher’s slip to Mia and Lilly’s improvised secret handshake — Heather Matarazzo shared behind-the-scenes stories as The Princess Diaries celebrates its milestone 25th anniversary.

I’m a pop-culture writer covering everything from TV and movies, to music, Broadway, books, and games.

By Mia's side was her megaphone-wielding, cable-access-hosting best friend, Lilly Moscovitz, portrayed by Heather Matarazzo. From unforgettable quotes like "Not you, I don't even know you!" to her public-access show Shut Up and Listen, Lilly became one of the film's most memorable characters.

To celebrate The Princess Diaries' 25th anniversary, I caught up with Heather to look back on making the Disney classic and hear the behind-the-scenes stories of some of its most iconic moments.

Heather: Annie and I knew each other from our days in New York, where we'd see each other at auditions. So when we did the chemistry read, we were already quite familiar with one another.

I don't have a specific recollection of the audition itself, but I do remember going to what was then called the Falcon Theatre, which is now the Garry Marshall Theatre, to meet with Annie and [director] Garry. I remember spending the afternoon with Annie in a rehearsal space in Toluca Lake.

Heather: (Laughs) People need to understand that I didn't write it. I was 17 years old. I didn't have the power to say, "This doesn't work." So there are definitely some things that are quite cringeworthy.

With that said, Lilly had more self-awareness at 15 or 16 than most adults I know. She was aware enough to recognize that her character flaws were getting the better of her and that she needed an attitude adjustment. She's the one who essentially pushed Mia to receive her title because she knew the power she had to effect change.

Teenage friendships are still about learning who you are. There were definitely some toxic moments, but luckily, she didn't carry those with her. I think she did much better in the second movie than she did in the first.

Heather: Garry really loved to keep the pace moving, so we were given a direction to just walk up and down these bleachers and talk. When you're in San Francisco in the fall, there's bound to be rain, if not mist. If you add mist with metal bleachers, falls are sometimes going to happen.

She handled it like such a pro. You're only as good as the scene partner you're working with, and we kept going. That whole sequence is genuine.

Heather: That was fully, fully, fully improvised.

It's rare to have a workmate that you have such natural chemistry with, and I think that's one of the reasons the relationship between Lilly and Mia works so well. Annie and I had a natural chemistry, and there was a freedom to just explore. To me, that's the best kind of partnership there is.

We were encouraged to improvise. Garry was very much in the moment, like, "Let's try this. Let's try this," to punch up the funny and make the moment land. It kept everything very fresh.

Heather: I tell this story again and again because it really emphasizes who he was. We were filming through Thanksgiving and Christmas, and up until The Princess Diaries, I'd mostly been doing independent films (laughs) where you're lucky to get a sheet as you change behind a dumpster and have two-day-old bread on the craft services table.

I remember we stopped shooting early one afternoon, and I was confused because I didn't know what was going on. Then all of a sudden, there was this mini Thanksgiving Day parade that Garry had put together. He invited all the families and children of the crew, and he was in the final car dressed as Santa Claus.

When you're making a movie, you're sometimes away from your family for two, three, or even four months at a time. Garry was very adamant that family came first.

That was a real eye-opener for me. It showed his generosity and kindness, and that filmmaking can be quite joyful.

Heather: Julie is an incredible actor. She's iconic, and I've been a fan of hers since The Sound of Music and Victor/Victoria.

She has such poise and such grace, and she's also incredibly hilarious and incredibly down to earth. I think the moment with Julie on the San Francisco trolley car was absolutely hilarious. "Goodbye, trolley people!" Watching Clarisse and Joe [Héctor Elizondo] have their moment was lovely as well.

There's that saying, "Don't meet your heroes," but she's definitely an exception to that rule.

Heather: One line that I get stopped about often is, "Not you, I don't even know you!"

We were doing the scene, and Garry wanted me to say something. Debra Martin Chase just threw out that line, and it was magic. It worked so well.

Heather: The ballroom scene has great emotion. Lilly's having a moment where she's watching her best friend step into her power, and there's nothing more beautiful than that.

(Laughs) But with filming, I think it was a marble floor, and by the end of the day our hips, our calves, and our feet were devastated.

Heather: I believe I kept Lilly's backpack and also the red sunglasses.

Heather: I think she'd be in the Amazon with maybe a flip phone, just completely off-grid, cheering on the orcas as they take down billionaire yachts.

Keep up with Heather on Instagram, @heathermatarazzo.

Note: This interview has been edited for length and clarity.