Anthony Edwards reveals his favorite prank by George Clooney and the ER team

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You might not think that a serious medical drama like ER would be a very funny show to work on, but Anthony Edwards says the cast was “always laughing.”

“That’s the best memory of ER is that we laughed so much,” Edwards tells host Lola Ogunnaike when he joined her on PeopleTV’s Couch Surfing. “We were always laughing. I think because the subject material was so heavy that we were always looking for ways to laugh.”

Edwards says pranks were extremely common on the show, but not just because costar George Clooney is a renowned prankster. “It also felt like we were in a submarine because so much took place on that one set so were always inside,” Edwards explains. “So you get a little stir crazy, and I mean, the classic was putting vaseline on the phone.”

Though Edwards notes one of the best pranks came when they managed to scare a guest actress who was portraying a mother in labor. “When she gave birth and we’d been bringing up this fake baby, we brought up the alien baby,” he remembers. “I never heard someone scream as loud as she did at this green baby.”

Edwards says initially no one on the show had any idea it would take off the way it did. They were too busy trying to learn the medical jargon and keep up with the pace of filming. “We were so lost at the time,” he says. “Everything was so foreign — all the medical was really hard to learn. I had no idea what the layout was. We were lost, but we knew that we were trying to make it real. It wasn’t until we saw it cut together that we realized it was something super special.”

Watch the clip above for more.