From the very start of Brooklyn Nine-Nine, Jake Peralta was known as the precinct’s sharpest and most immature detective. He was smart, witty, and downright funny. Samberg portrayed the character of Jake, the life and soul of the 99th precinct, whose antics never fail to put a smile on people's faces. His goofiness and fast-talking banter, along with his sharp detective skills, made him one of the most loved characters in the show and ensured that he remained amusing throughout.
Samberg's character, Jake, would sass back to his colleagues in a more entertaining way, and that only Samberg could accomplish, bringing such leaps of humour to Brooklyn Nine-Nine. It is the unapologetic improvisational spirit that Samberg exudes on the show that moulded some of the best moments in the show, and let me tell you: there are many. One of the highlights of the show has to be: “Cool, cool, cool."
Jake's 'Cool, Cool, Cool' catchphrase is a genius improvisation in Brooklyn Nine-Nine

The line “cool, cool, cool” does not appear in the Brooklyn Nine-Nine script. It was Kenny Samberg’s response to a line Andy Samberg used jokingly on set to rile up some laughs during productions, and was said during filming instead of ad-libbing with the cast. According to a Brooklyn Nine-Nine behind-the-scenes video on their official YouTube channel, Samberg said the phrase several times as it landed perfectly. Since it was well-received every time he said it, the writers chose to embrace it.
The catchphrase stands out for Jake because it is remarkably relatable to his character. He usually uses it when trying to deflect embarrassment, like after blundering or experiencing some social faux pas. It’s the exact type of line that would come out of someone’s mouth for the sake of saying it, but with Jake, it is rather effortless, and comes off very ‘in-character.’
Improvised humour that feels scripted

“Cool, cool, cool” saves its brilliance in the nuance beneath it. It is not a grand gesture or a physical confrontation, but rather an awkward verbal tic that isn’t accompanied by any subtle delivery. It is mainly meant to describe Jake, who always attempts to downplay any tension while trying to be in control, which is always crucial in the essence of his character.
Adding to the irony, as well as the catchphrase, is the fact that it was never meant to be a catchphrase in the first place. This improvisation is gold, especially from someone who understands his character very well, and enhances storytelling much better than scripted dialogue.
A nod to Samberg’s comedy roots

He did not receive this role by coincidence because Samberg was widely known before Brooklyn Nine-Nine. The man used to have a huge presence in humour circles. Alongside Saturday Night Live, Samberg was the core member of The Lonely Island, giving him a reputation for his absurdity, timing, and ridiculously humorous repetition.
Viewers of Hot Rod (2007) will recall that Samberg made cool beans famous with non-stop repetition. The new phrase "cool, cool, cool" has secured a similar sensibility from the famous "cool beans" scene of his earlier work, even though they are not related. Samberg shows his skill at such humour in this performance- he speaks dryly at first until his performance takes it from ordinary to memorable.
Samberg’s improvisation makes Brooklyn Nine-Nine feel alive

In network comedies, which are tightly written to bind the story together, improvisation is not easy to fold into the mix. Samberg’s improvised additions, such as the famous “cool, cool, cool,” weren’t permitted, but they became integral to the show’s character. That really speaks to the depth of his comedic instincts and the showrunners’ faith in his ability.
By getting inside Jake like this, Samberg imbued the character with facets that transcended how the show was written. This lets us in on the real secret of the show: “Cool, cool, cool” is more than a catchphrase. It’s a coping mechanism, a comic beat, and a hilarious, beautiful encapsulation of who Jake Peralta is.