Mayim Bialik and Johnny Galecki recreate their first on-screen kiss from 'Blossom' days

'Big Bang Theory''s Mayim Bialik, Johnny Galecki Recreate 'Blossom' Kiss

Kaley Cuoco isn't the only Big Bang Theory star who has a history with Johnny Galecki.

The cast of the hit CBS show appeared altogether on Wednesday's Conan, and things got a little awkward when the host brought up Mayim Bialik's on-screen kiss with Galecki when they were both on the hit '90s sitcom, Blossom.

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The actors were just 14 when they shared their first on-screen smooch. "It might have been my first real-life kiss also," Bialik admitted.

"Do it again!" urged their Big Bang Theory co-star, Kunal Nayyar. Jim Parsons further quipped, "What kind of show is this?"

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Bialik and Galecki eventually gave in and recreated the kiss, and they've certainly improved over the past decades.

Going along with the gag, Parsons and Cuoco also attempted an on-screen lip lock.

See more photos of the "Big Bang Theory" cast:

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Mayim Bialik and Johnny Galecki recreate their first on-screen kiss from 'Blossom' days
LOS ANGELES - APRIL 19: 'The Line Substitution Solution' -- Pictured: Trevor (Blake Anderson), Sheldon Cooper (Jim Parsons), Leonard Hofstadter (Johnny Galecki), Howard Wolowitz (Simon Helberg) and Rajesh Koothrappali (Kunal Nayyar). Sheldon hires Stuart to spend the day with Amy when he'd rather go to a movie screening. Also, Leonard's mother, Beverly (Christine Baranski), comes to town and Penny struggles to make a connection with her, on THE BIG BANG THEORY, Thursday, May 5 (8:00-8:31, ET/PT) on the CBS Television Network. (Photo by Michael Yarish/CBS via Getty Images)
LOS ANGELES - APRIL 19: 'The Line Substitution Solution' -- Pictured: Sheldon Cooper (Jim Parsons), Leonard Hofstadter (Johnny Galecki), Stuart (Kevin Sussman) and Howard Wolowitz (Simon Helberg). Sheldon hires Stuart to spend the day with Amy when he'd rather go to a movie screening. Also, Leonard's mother, Beverly (Christine Baranski), comes to town and Penny struggles to make a connection with her, on THE BIG BANG THEORY, Thursday, May 5 (8:00-8:31, ET/PT) on the CBS Television Network. (Photo by Michael Yarish/CBS via Getty Images)
LOS ANGELES - APRIL 19: 'The Line Substitution Solution' -- Pictured: Sheldon Cooper (Jim Parsons), Howard Wolowitz (Simon Helberg), Rajesh Koothrappali (Kunal Nayyar) and Leonard Hofstadter (Johnny Galecki). Sheldon hires Stuart to spend the day with Amy when he'd rather go to a movie screening. Also, Leonard's mother, Beverly (Christine Baranski), comes to town and Penny struggles to make a connection with her, on THE BIG BANG THEORY, Thursday, May 5 (8:00-8:31, ET/PT) on the CBS Television Network. (Photo by Michael Yarish/CBS via Getty Images)
HOLLYWOOD, CALIFORNIA - MARCH 16: (L-R) Moderator Alie Ward, executive producers Chuck Lorre, Steven Molaro, Bill Prady, actors Mayim Bialik, Jim Parsons, Kaley Cuoco, Johnny Galecki, Simon Helberg, and Kunal Nayyar attend The Paley Center For Media's 33rd Annual PALEYFEST Los Angeles ÃThe Big Bang Theory' at Dolby Theatre on March 16, 2016 in Hollywood, California. (Photo by Matt Winkelmeyer/Getty Images)
BEVERLY HILLS, CA - MARCH 09: (L-R) Actors Jim Parsons, Melissa Rauch, Kunal Nayyar, Kaley Cuoco, Simon Helberg, Mayim Bialik and Johnny Galecki perform onstage during the 24th and final 'A Night at Sardi's' to benefit the Alzheimer's Association at The Beverly Hilton Hotel on March 9, 2016 in Beverly Hills, California. (Photo by Jesse Grant/Getty Images)
MUST SEE TV: AN ALL-STAR TRIBUTE TO JAMES BURROWS -- Pictured: (l-r) Kaley Cuoco, Simon Helberg, Johnny Galecki, Jim Parsons -- (Photo by: Trae Patton/NBC/NBCU Photo Bank via Getty Images)
LOS ANGELES - FEBRUARY 2: 'The Positive Negative Reaction' -- Bernadette is concerned when Wolowitz freaks out over her pregnancy announcement, and Wolowitz is convinced he must make more money to provide for the baby, on THE BIG BANG THEORY, Thursday, Feb. 18 (8:00-8:31 PM, ET/PT) on the CBS Television Network. Pictured left to right: Kunal Nayyar, Simon Helberg, Johnny Galecki and Jim Parsons (Photo by Sonja Flemming/CBS via Getty Images)
LOS ANGELES - JANUARY 19: 'The Valentino Submergence' -- Sheldon and Amy host a live Valentine's Day episode of Fun with Flags, Leonard and Penny grapple with getting older, Howard and Bernadette find a surprise in their hot tub and Raj is torn between Emily and the cute girl he met at the Comic Bookstore, on THE BIG BANG THEORY, Thursday, Feb. 11 (8:00-8:31 PM, ET/PT), on the CBS Television Network. Pictured left to right: Johnny Galecki, Simon Helberg, Jim Parsons and Kunal Nayyar (Photo by Monty Brinton/CBS via Getty Images)
LOS ANGELES - FEBRUARY 8: 'The Celebration Experimentation' -- After more than nine years together, the gang finally celebrates Sheldon's birthday, surprising him with a special guest, on the 200th episode of THE BIG BANG THEORY, Thursday, Feb. 25 (8:00-8:31 PM, ET/PT) on the CBS Television Network. Pictured left to right: Jim Parsons, Kunal Nayyar, Sara Gilbert, Kevin Sussman, Adam West, Simon Helberg, Melissa Rauch, John Ross Bowie, Wil Wheaton, Johnny Galecki and Kaley Cuoco (Photo by Monty Brinton/CBS via Getty Images)
LOS ANGELES - FEBRUARY 2: 'The Positive Negative Reaction' -- Bernadette is concerned when Wolowitz freaks out over her pregnancy announcement, and Wolowitz is convinced he must make more money to provide for the baby, on THE BIG BANG THEORY, Thursday, Feb. 18 (8:00-8:31 PM, ET/PT) on the CBS Television Network. Pictured left to right: Simon Helberg, Kunal Nayyar, Jim Parsons and Johnny Galecki (Photo by Sonja Flemming/CBS via Getty Images)
LOS ANGELES - AUGUST 30: 'The Pulled Groin Extrapolation' -- Sheldon and Penny wonder how they'll get along when Leonard goes to a wedding as Amy's date. Meanwhile, Howard (Simon Helberg, left) and Bernadette (Melissa Rauch, right) spend the weekend with Mrs. Wolowitz, on THE BIG BANG THEORY, Thursday, Sept. 29 (8:00-8:31 PM, ET/PT) on the CBS Television Network. (Photo by Richard Cartwright/CBS via Getty Images)
LOS ANGELES - SEPTEMBER 23: 'The Workplace Proximity' -- Howard (Simon Helberg, left) finds himself sleeping on Raj'™s couch after a fight with Bernadette, on THE BIG BANG THEORY, Thursday, Oct. 17 (8:00 -“ 8:31 PM, ET/PT) on the CBS Television Network. Also pictured: Johnny Galecki (right) (Photo by Monty Brinton/CBS via Getty Images)
LOS ANGELES - APRIL 15: 'The Gorilla Dissolution' -- Howard (Simon Helberg, left) and Bernadette (Melissa Rauch, right) struggle to care for Mrs. Wolowitz, on THE BIG BANG THEORY, Thursday, May 8 (8:00-8:31 PM, ET/PT) on the CBS Television Network. (Photo by Sonja Flemming/CBS via Getty Images)
LOS ANGELES, CA - SEPTEMBER 18: Kaley Cuoco is seen at 'Jimmy Kimmel Live' on September 18, 2014 in Los Angeles, California. (Photo by RB/Bauer-Griffin/GC Images)
LOS ANGELES, CA - SEPTEMBER 20: Kaley Cuoco is seen in Los Angeles on September 20, 2014 in Los Angeles, California. (Photo by Bauer-Griffin/GC Images)
LOS ANGELES, CA - SEPTEMBER 20: Kaley Cuoco is seen in Los Angeles on September 20, 2014 in Los Angeles, California. (Photo by Bauer-Griffin/GC Images)
LOS ANGELES, CA - AUGUST 25: Actress Kaley Cuoco (R) and husband Ryan Sweeting (L) attend HBO's 2014 Emmy after party at The Plaza at the Pacific Design Center on August 25, 2014 in Los Angeles, California. (Photo by Barry King/FilmMagic)
GOOD MORNING AMERICA - Rihanna, Steve Martin and Jim Parsons are all guests on 'Good Morning America,' 3/13/15, airing on the ABC Television Network. (Photo by Lou Rocco/ABC via Getty Images)
LOS ANGELES, CA - AUGUST 25: Actress Kaley Cuoco arrives to the 66th Annual Primetime Emmy Awards at Nokia Theatre L.A. Live on August 25, 2014 in Los Angeles, California. (Photo by C Flanigan/Getty Images)
BURBANK - JULY 23: Gallery Promo Coverage of CBS' THE BIG BANG THEORY, scheduled to air on the CBS Television Network. Pictured: Simon Helberg as Howard Wolowitz. (Photo by Monty Brinton/CBS via Getty Images)
BEVERLY HILLS, CA - DECEMBER 18: Actress Kaley Cuoco-Sweeting arrives at The PEOPLE Magazine Awards at The Beverly Hilton Hotel on December 18, 2014 in Beverly Hills, California. (Photo by Jon Kopaloff/FilmMagic)
NEW YORK - MAY 18: CBS announces their new fall schedule. (Jeffrey R. Staab/CBS via Getty Images) *** CBS presented its 2016-17 prime time schedule today (May 18) at Carnegie Hall, where many of the Networks new and returning series stars were in attendance. Pictured L-R: Melissa Rauch, Mayim Bialik, Simon Helberg, Kaley Cuoco, Jim Parsons, and Johnny Galecki from THE BIG BANG THEORY *** Melissa Rauch;Mayim Bialik;Simon Helberg;Kaley Cuoco;Jim Parsons;Johnny Galecki
LOS ANGELES - SEPTEMBER 9: 'The Hook-Up Reverberation' -- Raj's honesty about his past comes back to haunt him after his girlfriend, Emily, is cold to Penny. Also, the guys consider becoming part-owners in Stuart's comic book store, on THE BIG BANG THEORY, Monday, Oct. 6 (8:00-8:31, ET/PT), on the CBS Television Network. Pictured left to right: Laura Spencer, Simon Helberg, Melissa Rauch, Mayim Bialik, Jim Parsons, Johnny Galecki and Kaley Cuoco-Sweeting (Photo by Sonja Flemming/CBS via Getty Images)
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WATCH: Kaley Cuoco Says She's in a 'Much Better Place' Since Split From Ryan Sweeting

It's no secret that Galecki and Cuoco dated when Big Bang Theory first started, but after the actress announced her split from husband, Ryan Sweeting, a new crop of romance rumors spread about the co-stars. "So sorry to disappoint, but no home wreckers or secret flings going on here," Cuoco responded via Instagram to the reports in January. "Me and @sanctionedjohnnygalecki are just the best of buds -- Leonard and Penny will just have to suffice!"

Kaley Cuoco Insists She Is 'Not Dating' Johnny Galecki in Instagram Post
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