The REAL story behind Heath Ledger's iconic '10 Things I Hate About You' singing scene will make you swoon

It’s hard to believe, but one of our favourite high school rom-coms, 10 Things I Hate About You has just turned 20 years old.

Wowee! Two whole decades!

Looking back, there is still one scene that will always make our hearts flutter and that is when a young Patrick Verona - played by Heath Ledger who was just 19 at the time – serenades Kat Stratford, played by Julia Stiles on the high school bleachers.

And there is a little known fact about the scene that makes it even more special: That Heath chose the song he sang himself!

In an interview with HuffPost for the movie's 20th anniversary, director Gil Junger revealed the actor’s wildly magnetic" performance came after the film’s creators were stuck tossing up between two songs, I Think I Love You by the Partridge Family and I Touch Myself by Divinyls.

• READ MORE: Here's what the cast of 10 Things I Hate About You look like now

However, Heath decided to go in a different direction completely on the day of the shoot, choosing to perform Frankie Valli’s classic, Can’t Take My Eyes Off You.

"Heath just surprised everyone with his commitment to that performance," Julia Stiles added in the same HuffPost interview.

We are very glad the Australian-born star went with that song rather than I Touch Myself, and it seems to are the movie’s makers.

"I think Heath decided that that wasn’t romantic enough, so he chose the Frankie Valli song, which was a much better call,", screenwriter Karen McCullah told the New York Times.

The swoon-worthy scene would not be the same without it!

Meanwhile, the cast members of 10 Things took to social media to reflect on the hit movie’s anniversary.

Actor Joseph Gordon-Levitt – who played the love sick character Cameron James – took to Instagram to write a sweet tribute.

"10 Things I Hate About You came out 20 years ago today. What a special summer it was making that movie with such wonderful people," the actor wrote.

Larisa Oleynik - who starred as Biana Stratford - took to Instagram to share her, "Mini high school reunion with the guy I took to the prom, the guy I punched at the prom, the guy with the Brie, the writers who created us, and the band that played on the roof. You know, as you do. Thanks to everyone who made this happen!"

David Krumholtz – who played geeky Michael Eckman – also shared a touching post about his co-star Heath, who sadly passed away in 2008.

He also shared another iconic snap from the film of his character with an unfortunate drawing on his face.

"Happy 20^th to 10 Things I Hate About You," he wrote alongside the hilarious snap.