In Knocked Up, Seth Rogen and Paul Rudd go to Las Vegas and have a terrible time. But Rogen had a better experience during a recent trip to Sin City, where he was filming the upcoming Apple TV+ series The Studio with Kathryn Hahn.

During Wednesday’s episode of Jimmy Kimmel Live guest hosted by Hahn, Rogen recounted a memorable evening spent tripping on acid while watching The Grateful Dead at the all-mighty Sphere. “It was normal Las Vegas for the first week and a half, and then one day, our casino was filled with bald men with ponytails and tie-dye shirts. We were like, ‘Oh, The Grateful Dead is here,’” he recounted. The Sausage Party: Foodtopia star did “a ton of acid” and watched the Dead perform in Sphere, which blew his “goddamn mind.”

Rogen wasn’t a Deadhead before the show, but he left a changed man. “It’s weird to hear a band for the first time and then [they] become your favorite band of all-time,” he told Hahn, who also attended the concert. “I don’t know this song, but it’s the best song I’ve ever heard in my entire life.”

“Dark Star” will do that to a person.

You can watch Hahn’s interview with Rogen above.

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