Mayim Bialik and Johnny Galecki were caught kissing… again!

The Big Bang Theory costars first locked lips on an episode of the 90s sitcom Blossom at age 14 — and the two relived that romantic throwback moment on Wednesday, Feb. 24 during an appearance on Conan!

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"We were both 14. We kissed," Mayim, 40, recalled of Johnny's guest star role on Blossom. "It might have been my first real life kiss," Mayim said, with Johnny, also 40, adding it was both stars' first stage kiss.

Watch the funny video below!