John Lithgow & William Shatner Pulled Epic Prank on ‘3rd Rock From the Sun’ Set (VIDEO)

Two years ago, Joseph Gordon-Levitt revealed that his former 3rd Rock From the Sun co-star John Lithgow had a real gift for getting everyone into panic mode on April Fool’s Day. Appearing on The Kelly Clarkson Show, the actor recalled when Lithgow had Gordon-Levitt’s mother convinced the prince of England was coming to the set of the show for a visit, and she went all-out to prepare. That turned out to be a prank, and she retaliated by putting a gaggle of crickets in his dressing room.

As it turns out, that wasn’t even the best fake-out Lithgow pulled on the set of the hit ’90s sitcom about a group of aliens living a middle-class life on Earth.

Lithgow was a guest on The Kelly Clarkson Show Friday, promoting his new PBS special, Art Happens Here, and he looked back on that incident and revealed another that really lifted tensions into the stratosphere.

“Joey’s mother called the NBC press department and said, ‘Nobody told me about this.’ And their response was, ‘Nobody told us about this!’ And word went out to Entertainment Tonight and everywhere that the prince was coming to our set. Everybody was in a rage. I considered it a huge success,” he remembered before diving into an even bigger prank involving William Shatner when guest-starred in Season 4’s “Dicks Big Giant Headache” in 1999.

“Bill Shatner came as a guest for a two-episode, hour-long special 3rd Rock. We’d already shot the first episode. And as I drove to the set on April 1st, I thought, ‘Oh my god, I haven’t planned anything.’ I called Bill, and I suggested that we spend the whole day bickering and sort of sniping at each other like something is really bugging us. We made up a fake story we were arguing about. And about 3 p.m. at the big network run-through where we presented the show that we were going to do in front of a live audience, it exploded into this huge fight between Shatner and me. The worst! ‘This is not Star Trek! This is 3rd Rock From the Sun!’… Off to our dressing rooms, bang! ‘I’m not coming back until that man apologizes,'” Lithgow told Kelly Clarkson.

“You should have seen the NBC executives. We’d already shot the first half of the show. We couldn’t lose Bill Shatner,” the actor continued. “And then, of course, we came out with an April Fool’s cake. Everybody was furious once again. But Shatner considered it the best acting he has ever done. It was great.”

The execs’ fury mustn’t have lasted too long, of course, because Shatner was brought back for three additional episodes in Season 5, including another two-part episode spectacular.

The Kelly Clarkson Show, weekdays, check local listings