15 Movie Quotes You Never Knew Were Ad-Libbed

The opening lines that were America's introduction to audible dialogue in a feature-length film were completely ad-libbed.

Though Gosling only does it with his friends while out, his suggestion to do the final move from Dirty Dancing made its way into the final cut.

Kelly was haunted by a neighbor who used a similar sing-song to taunt him, which led to him both making up this line and delivering it so terrifyingly.

While claiming to improvise the majority of his lines in this movie, this is far and away Paxton's best piece of ad-libbed excellence.

Welles ad-libbed an entire speech that was in neither the book nor the script and turned it into the most-quoted bit from the whole movie.

Bogey had uttered the line in a different movie, but it didn't land until he decided to add it to this one.

Director John Landis gave Belushi a cafeteria full of actors and no direction. Landis apparently knew comedy gold was about to be forged, though, because he did urge the cameraman to "stay with him" while Belushi was filling his tray.

Perhaps chalk it up to playing three different roles in the same film, but Sellers forgot Dr. Strangelove was wheelchair-bound and made up these lines the second he recognized his mistake.

Harold Ramis told Murray to narrate himself while golfing, so he made up every line of dialogue in the scene on the spot.

Williams's 16 hours of improv included 14 impressions and a Scottish accent — the one he'd famously use the following year in Mrs. Doubtfire — that cost this movie an Academy Award nomination for Best Adapted Screenplay.

Clemenza telling Rocco to "Leave the gun" after killing Paulie was in the script, but then Castellano doubled down with one of the most gangster lines of all time.

A true testament to Scheider's acting ability, he deadpanned this classic without any prompting from anyone.

The script called for "Just remember that, Leia, because I'll be back" as a response to Leia's "I love you," but we got this infinitely cooler gem instead.

Scorsese let Liotta and Pesci improvise the entire tense scene in order to get real reactions from all the actors surrounding them.

The script for this scene only had the words, "Travis looks in the mirror," so De Niro, inspired by a Brando flick and using an actor's technique to practice lines, made up every part of this scene.