"You do? Should we just get it over with now?" asked Zachary Quinto.
"Yeah. Ow! Oh my God!" asked Andy. "You really just slapped me, I have to say?"
"I'm sorry, it's just my instinct," said Zachary.
"Wow!" said Andy.
"That's where this night is going, baby!" said guest Aidy Bryant.
Umm, ouch. We can feel that one on the other side of the screen.
But as Zachary noted, Andy did ask to be slapped. Ask and you shall receive, Mr. Cohen.
And Andy probably should have seen that painful backhand coming.
Zachary's hand has gotten a lot of practice on the set of "The Slap," which focuses on the fallout after a man smacks another couple's misbehaving child. (Video via NBC / "The Slap")
But don't worry, he didn't actually slap the poor kid. Zachary told Entertainment Weekly, "The thing that was most important to everyone was the safety of the kids. ... There was clear communication with the kids. And then all the explosive anger and emotions was all done without the kids there."
Well, we wish we could say the same for Andy and his red cheek over there.
This video includes images from Getty Images.
WATCH: Zachary Quinto slaps Andy Cohen on 'WWHL'
Actor Zachary Quinto arrives for the screening of All Is Lost at the 66th international film festival, in Cannes, southern France, Wednesday, May 22, 2013. (AP Photo/Virginia Mayo)
Zachary Quinto attends 20th Century Fox panel for "Hitman: Agent 47" on Day 2 of Comic-Con International on Friday, July 25, 2014, in San Diego. (Photo by Chris Pizzello/Invision/AP)
Actor Peter Sarsgaard, left, and actor Zachary Quinto seen at The Hollywood Reporter Studio at Sundance on Saturday, Jan. 24, 2015 in Park City, Utah. (Photo by Dan Steinberg/Invision for The Hollywood Reporter/AP Images)
IMAGE DISTRIBUTED FOR CHASE SAPPHIRE PREFERRED - JZachary Quinto talks about the film "I am Michael" as director Justin Kelly looks on at the "Indiewire in Conversation" panel at Chase Sapphire on Main during the 2015 Sundance Film Festival Saturday, January 24, 2015, in Park City, Utah. (Photo by Jack Dempsey/Invision for Chase Sapphire Preferred/AP Images)
Charlie Carver, from left, director Justin Kelly, Zachary Quinto and James Franco pose for a portrait to promote the film, "I Am Michael", at the Eddie Bauer Adventure House during the Sundance Film Festival on Sunday, Jan. 25, 2015, in Park City, Utah. (Photo by Victoria Will/Invision/AP)
Zachary Quinto, a cast member in the television series "The Slap," poses at the NBCUniversal 2015 Winter TCA Press Tour at The Langham Huntington Hotel on Friday, Jan. 16, 2015, in Pasadena, Calif. (Photo by Chris Pizzello/Invision/AP)
NEW YORK, NY - SEPTEMBER 15: Zachary Quinto seen in New York City on September 15, 2014. Credit: RW/MediaPunch/IPX
Zachary Quinto attends the The Public Theaterâs annual gala at The Delacorte Theater on Monday, June 23, 2014 in New York. (Photo by Donald Traill/Invision/AP)
Zachary Levi, left, and Zachary Quinto attend the Drama League Awards on Friday, May 16, 2014 in New York. (Photo by Charles Sykes/Invision/AP)
Actor Zachary Quinto attends the opening night of "A Time To Kill" on Broadway on Sunday, Oct. 20, 2013 in New York. (Photo by Andy Kropa/Invision/AP)
Zachary Quinto arrives at the Annual Charity Day hosted by Cantor Fitzgerald and BGC Partners, on Wednesday, Sept. 11, 2013 in New York. (Photo by Ben Hider/Invision/AP)
Actor Zachary Quinto waves to fans during the Japanese premiere of his film "Star Trek Into Darkness" in Tokyo, Tuesday, Aug. 13, 2013. (AP Photo/Shizuo Kambayashi)
Director J.J. Abrams, left, British actress Alice Eve, second left, U.S actors, Chris Pine, third left, and Zachary Quinto, pose for photographers during a press conference for their film "Star Trek Into Darkness" in Tokyo, Tuesday, Aug. 13, 2013. (AP Photo/Itsuo Inouye)
Christina Hendricks and Zachary Quinto in the audience at the 65th Primetime Emmy Awards at Nokia Theatre on Sunday Sept. 22, 2013, in Los Angeles. (Photo by John Shearer/Invision for Academy of Television Arts & Sciences/AP Images)
U.S. actor Zachary Quinto takes a photograph with a fan after a press conference for his latest film "Star Trek Into Darkness" in Tokyo, Tuesday, Aug. 13, 2013.(AP Photo/Itsuo Inouye)
Actor Zachary Quinto attends a special screening of Radius TWC's "Lovelace" hosted by The Cinema Society and MCM on Tuesday, July 30, 2013 in New York. (Photo by Evan Agostini/Invision/AP)
Sarah Paulson, left, and Zachary Quinto speak on stage at the Critics' Choice Television Awards in the Beverly Hilton Hotel on Monday, June 10, 2013, in Beverly Hills, Calif. (Photo by Frank Micelotta/Invision/AP)
Actor Zachary Quinto attends a screening of "I'm So Excited" presented by Girard-Perregaux and The Cinema Society on Thursday, June 6, 2013 in New York. (Photo by Andy Kropa/Invision/AP)
Actors Chris Pine, left, and Zachary Quinto speak to the media at the "Star Trek Into Darkness" premiere at AMC Loews Lincoln Square on Thursday, May 9, 2013 in New York. (Photo by Evan Agostini/Invision/AP)
Actor Zachary Quinto attends the "Star Trek Into Darkness" premiere at AMC Loews Lincoln Square on Thursday, May 9, 2013 in New York. (Photo by Evan Agostini/Invision/AP)
Zachary Quinto poses for a portrait session at the Corinthia Hotel in London on Saturday, May 4, 2013. Zachary Quinto starred in the latest release of the Star Trek film franchise: Into Darkness. (Photo by Richard Chambury/Invision/AP)
Chris Pine, Alice Eve, Zachary Quinto and Zoe Saldana arrive for the Star Trek Into Darkness: UK Premiere in London, Thursday, May. 2, 2013. (Photo by Jonathan Short/Invision/AP)