By Annie Barrett
August 25, 2011 at 06:09 PM EDT

Party time! The cast of Party Down makes a special appearance on tonight’s Childrens Hospital (Adult Swim, 12 a.m. ET). Lizzy Caplan, Martin Starr, and Ryan Hansen — along with Ken Marino and Megan Mullally, who already star in Hospital, show up to cater Dr. Glenn Richie’s (Marino) later-in-life Bar Mitzvah.

“I couldn’t believe all the Party Down actors showed up!” Marino marvels to EW over the phone. “I love the guy who plays Ron. He came in. He was kind of a d—, actually, in real life.”

Getting the gang together was awesome, but bittersweet, Marino says. Starz canceled the underrated and woefully under-viewed Party Down after two hilarious seasons. “We had so much fun doing that little scene,” Marino says of tongiht’s Hospital cameo. “And then we were like, goddammit, why is this show not happening anymore?” Another huge disappointment: Marino’s hair. “We had to try to fake my Ron Donald haircut because I had my Glenn Richie haircut,” he says. “It was too long and looked a little ridiculous.”

As for a possible Party Down movie — which Marino called “a go” during the Childrens Hospital panel at July’s Comic-Con — things are looking good. “They’re moving in the right direction,” Marino says. “Nothing’s ‘a go.’ I don’t even know what ‘a go’ is. But I will say this: It looks positive, and it it happens, I’d be thrilled. I know everybody in the cast would too.”

In the meantime, wouldn’t it be great if Ron Donald just opened that Soup R’ Crackers he’s always dreamed of… adjacent to or even inside Childrens Hospital? “You’re blowing my mind,” Marino says. “I’ll pitch it.”

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Comic-Con 2011: EW’s ‘Childrens Hospital’ chat, a.k.a. the funniest thing you’ll watch all day