Emily Blunt is ready to kiss and tell.

The British actress spoke candidly about how chemistry with a costar does not always equate to fondness. 

"I've had chemistry with people I haven't liked. At all," she shared on "The Howard Stern Show."

EMILY BLUNT AND JOHN KRASINSKI SPARK INTERNET FRENZY AS FANS ANALYZE RED CARPET CONVERSATION

Emily Blunt soft smiles on the carpet in a sparkling orange one-shoulder dress

Emily Blunt spoke candidly about having natural or manufactured chemistry with her costars. (Jon Kopaloff/Getty Images)

"Who?" Stern inquired.

"I'm not gonna tell you," Blunt answered. Working in the film industry for more than two decades, Blunt has starred opposite many big names, including Tom Cruise in "Edge of Tomorrow," Colin Firth in "Arthur Newman" and Matt Damon in "The Adjustment Bureau." She also costarred alongside husband John Krasinski in "A Quiet Place," although their characters did not technically lock lips on camera. 

Emily Blunt in a white dress on the Oscars carpet with husband John Krasinski

John Krasinski and Emily Blunt have been married since 2010. They starred in Kransinski's film, "A Quiet Place" together in 2020. (Jeff Kravitz/FilmMagic/Getty Images)

"I have had chemistry with people who...I have not had a good time working with them," she added, without disclosing their identity. 

"Sometimes it's a strange thing. Sometimes you could really, really like someone, and you could be pals, and you could have a rapport that's really effortless, but it doesn't translate onscreen and chemistry is this strange thing. It's an ethereal thing that you can't really bottle up and buy or sell. It's like there or it's not."

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Emily Blunt in a red strapless dress soft smiles on the carpet with Tom Cruise in a black suit and tie

Emily Blunt and Tom Cruise starred in the 2014 film "Edge of Tomorrow" together. The two kiss in the movie. (Jim Spellman/WireImage/Getty Images)

Colin Firth in a dark suit looks slightly over his shoulder as Emily Blunt in black looks up at him lovingly

Colin Firth and Emily Blunt starred in the rated-R film, "Arthur Newman" in 2012, in which they play love interests. (Eric Charbonneau/WireImage/Getty Images)

Emily Blunt in a peach ruffled dress laughs with Matt Damon in a black suit and shirt and eyeglasses

Emily Blunt and Matt Damon at the premiere of their movie,"The Adjustment Bureau" in 2011. They play lovers in the film. (Getty Images)

However, Blunt said "you can manufacture" the chemistry to some extent. "It's just easier when you have a natural rapport with someone," she explained. "My feeling is I've got to find something I love about everybody. I have to find something ... Even if it's one thing," she emphasized.

"It might be like they have a nice laugh…or I like how they speak to people. They’re polite," she offered as examples. "I mean, it might be something random, but find something you love about that person or something you love about them as the character…And then kind of lean into that."

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Emily Blunt looks serious on the carpet in a red halter dress and gold chain necklace

Emily Blunt confesses she has felt sick after kissing certain costars, but she did not reveal who. (VALERIE MACON/AFP via Getty Images)

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"Have you ever had to kiss someone on screen and you wanted to throw up? Like it was that bad," Stern asked.

"Absolutely. Absolutely," Blunt confessed.

Stern dug deeper, asking, "Do you go home and shower and, like, just try to get it out of your mind? I can't imagine."

"I wouldn't say it's sort of extreme loathing," she said with a brief laugh. "But I've definitely not enjoyed some of it."

Ryan Gosling in a dark red shirt and suit looks stoic on the camera with a smiling Emily Blunt in a white patterned dress

Emily Blunt is currently promoting her upcoming film, "The Fall Guy," with Ryan Gosling. In the trailer for the flick, the duo share a smooch. (Stephane Cardinale - Corbis/Corbis via Getty Images)

Blunt's latest costar is Ryan Gosling, whom she stars alongside in the upcoming film, "The Fall Guy." Of Gosling, Blunt said she feels "very lucky to be friends with a gem of a person like him."