Dialogue can change the course of an entire television show. From confessions to one-liners, what a character says can reveal their personality, motivations, and inner thoughts. These words are carefully crafted in a writers' room, selected and edited to suit the story the writers are trying to tell.

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However, there have been many occasions where an actor is so in tune with their character that they ad-lib on the spot. While these improvisations don't always make the final cut, there are some memorable lines that were made up by the actors. These improvised lines range from hilarious to tragic and show how deeply actors can connect with their characters.

10 "Don't Ya, Big Boy?" - Joseph Quinn

Stranger Things

Eddie Munson smiling in Stranger Things 4

Fans of Stranger Things are wary of new characters, yet Joseph Quinn's Eddie Munson became an instant fan-favorite in Season 4. Eddie's friendship with Dustin causes some friction between him and Steve, as both characters are unknowingly jealous of the other's bond with Dustin.

Throughout the season, that friction gives way to budding friendship and even straight-up flirtation, mostly from Eddie. When the Party has to steal an RV, Eddie assures Robin he won't be driving. The line originally had Eddie saying, "Harrington's got her," but Quinn improvised the "Don't ya, big boy?" line. The words genuinely surprised Joe Keery and Maya Hawke.

9 "Today Is Your Turn To Lose" - Oscar Isaac

Moon Knight

Jake Lockley in Moon Knight.

Oscar Isaac has been credited for many of the character decisions in Marvel Studios' Moon Knight. He decided to make Steven Grant British while Marc Spector was American. Fans and critics alike have raved over Isaac's performance, proving the actor understood the character and could execute a highly creative vision.

In the season finale, audiences were finally able to meet the third alter, Jake Lockley. While his single line of dialogue was in the script, it was Isaac's idea to have Lockley speak Spanish. Isaac pushed for it until the director agreed to keep it in the final cut.

8 "You Could Have 'Network Connectivity Problems'" - Chris Pratt

Parks And Recreation

Chris Pratt in Parks & Rec.

While Marvel Studios' Guardians of the Galaxy launched Chris Pratt into stardom, many comedy fans already knew him from Parks and Recreation. Three years before his MCU debut, Pratt pulled off what the series' executive producer refers to as "the show's funniest joke."

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Leslie is sick with the flu, and when she's being escorted out of her office, she passes by Pratt's Andy. He originally was not supposed to speak in the scene, but with the camera on him, Pratt pointed to his computer and said, "Leslie, I typed your symptoms into the thing up here, and it says you could have 'network connectivity problems.'"

7 Robin Williams And Billy Crystal's Entire Scene

Friends

Robin Williams and Billy Crystal with Rachel, Chandler, and Phoebe in Central Perk

No one can question that Robin Williams was a comedic genius. His entirely unplanned cameo in Friends proves that. Williams and Billy Crystal were working in the studio next door to the Friends set and were asked to do a brief appearance on the show.

With it being so last minute, Williams and Crystal improvised their entire scene, which is considered one of the series' best cold opens. The entire exchange was so outrageous and random that even the main cast members were hanging onto their guests' every word as they all sat on the Central Perk couch.

6 "Hot Damn!" - Andre Braugher

Brooklyn 99

Captain Raymond Holt announces the fourth Halloween heist Brooklyn Nine-Nine

Braugher's Captain Holt was not usually one for shenanigans. Regardless, his monotonous voice and deadpan expressions executed his humor hilariously. As such, any time Captain Holt showed any sort of emotion, it had a high comedic impact on viewers.

In one of Brooklyn Nine-Nine's most memorable cold opens, the 99 theorize why the always-punctual Santiago is late for work. Everyone comes up with fun and ridiculous possibilities, while Holt suggests she got stuck at the bank. When Santiago arrives, she admits there was a line at the bank. In response, Braugher improvised a victorious and overly-energetic response, "Hot damn!"

5 "I, Ross, Take Thee Rachel" - David Schwimmer

Friends

Ross Geller demonstrating 'unagi' in Friends

Friends is famous for many iconic catchphrases and one-liners, but one of its greatest bits of dialogue was a complete accident. Ross and Rachel's relationship went through several ups and downs in the series, with one of the lowest points being Ross and Emily's disastrous wedding.

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During rehearsals, David Schwimmer accidentally mixed up Emily and Rachel's names. The writers realized that the comedic chaos they could create by writing that mix-up into the wedding scene was too good to pass up. It ended up being the final moment of that season.

4 "My Dad's Dead?" - Jason Segel

How I Met Your Mother

How I Met Your Mother's Lily and Marshall

In the DVD commentary for How I Met Your Mother, it was revealed that Jason Segel had no idea his character's father was going to die. He did not read Alyson Hannigan's lines for the scene. When Hannigan, who played Lily, broke the news to Marshall, his reaction to the news was very much Segel's genuine reaction.

"My dad's dead?" Segel asked. He then went on to say, "I'm not ready for this." It was a beautiful display of emotion that can only happen when an actor is truly feeling the same thing as their character.

3 "Close Your Eyes, Baby" - Susanna Thompson

Arrow

Moira Queen on Arrow

Regardless of what critics and viewers thought of Arrow, one thing that cannot be denied is that the show knew how to make a death scene incredibly sad. One of the first tragic deaths in the series was Moira Queen, Oliver and Thea's mother.

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Thompson revealed she improvised the heart-wrenching "close your eyes, baby" line ahead of filming. She thought about how Moira wouldn't want her daughter to witness her murder and added the line during rehearsals. It's a perfect example of an actor fully embodying their character.

2 Patton Oswalt's Proposal For Star Wars Episode VII

Parks And Recreation

Patton Oswalt on Parks and Rec

Before Disney announced The Force Awakens, Patton Oswalt appeared in an episode of Parks and Recreation and shared his vision for how a Star Wars sequel should start. The extended cut of the scene runs for almost nine minutes.

Oswalt's character uses his Star Wars dream as a filibuster. An overlap of Parks and Rec fans and Star Wars fans noted that Oswalt's speech directly resembled a scene from The Book of Boba Fett almost 10 years later.

1 "I Love You, Man" - Joseph Quinn

Stranger Things

Dustin, Mike, and Eddie Munson in Stranger Things 4 Vol. 1.

Proving his dedication both to Eddie Munson and Stranger Things, Joseph Quinn gave fans yet another amazing improvised line in the season 4 finale. In one of the saddest death scenes in Stranger Things, Dustin is holding and crying over Eddie as the older teen dies from his wounds.

Recognizing the special friendship Eddie and Dustin had and how important Eddie was to Dustin, Quinn added the "I love you, man" line to the scene. This prompted Gaten Matarazzo to quietly respond with, "I love you, too." Fans were heartbroken during this scene.

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