Watch as Seth Rogen gives Conan O'Brien a hit of his joint live in studio

And then naturally, the spliff was passed around

'This is the kind of thing you do when you know it's over for you."

Seth Rogen managed to get Conan O'Brien to take a drag of a joint during his interview with the presenter last night. The toke taking occurred after the presenter asked what he should do now that he's about to retire.

Seth, who hasn't tried to hide his use of the recreational drug over the years, and who owns a marijuana company named Houseplant, whipped out a spliff after Conan asked him what kind of "fine herb" would suit him best.

Conan said that any time he'd previously taken drags of weed, it didn't do much - so Seth gives him one from his own pocket.

Seth is visibly ecstatic that the presenter agreed to smoke a joint with him during the interview, and after the doobie is whipped out, he struggles to keep in his laughter. After taking a toke, Conan asks, "Is it supposed to burn?"

Seth later tweeted that the moment was "genuinely unplanned" and that he was "terrified that I got him too high".

We can't help but wonder what would have happened if Seth Rogen had joined Ryan Tubridy live in studio on 'The Late Late Show' this season (as opposed to via video link) if the interview would have taken a similar path...

Here's how the Seth Rogen and Conan O'Brien moment went down.

Conan O'Brien is wrapping up his presenting career with TBS later this week, with his final episode of his talk show expected to air tomorrow on Thursday, June 24. His final guest on the show will be Jack Black.