Why is everyone from The Big Bang Theory kissing each other on Conan?

If this doesn’t take TRPs through the roof, we don’t know what will. The Big Bang Theory’s entire star cast recently appeared The Tonight Show with Conan O’Brien but the chat quickly escalated to a kissing orgy.

On the occasion of their 200th episode celebration, Mayim Bialik and Johnny Galecki were reminded of their first on-screen kiss with each other back in the 90’s on the show Blossom.

Johnny Galecki and Mayim Bialik share their first kiss on 90’s show Blossom. (YouTube)

The 40-year-old actor said that it was the first stage kiss for both of them, to which Bialik added that the 1991 smooch was her first ‘real-life kiss, also’. Kunal Nayyar dared the pair to ‘do it again’ and while they initially declined, it wasn’t long before they were locking lips in a lengthy snog.

Read: Big Bang Theory’s Jim Parsons is richest TV actor

Mayim Bialik and Johnny Galecki lock lips for a lengthy kiss on The Tonight Show. (YouTube)

Sensing the mood in the room, Kaley Cuoco and Jim Parsons and Melissa Rauch and Kunal Nayyar also got in on the action, leaning in to an all-star snog-fest on the couch.

Read: Sheldon, Amy to engage in some ‘coitus’ on Big Bang Theory

Watch the heat rise in the room here: