"I think if Ryan could retire from acting and be a prankster, he would consider it," Jim Parrack, who plays Hoyt Fortenberry on the HBO hit, tells PEOPLE.
So what was one of Kwanten's more memorable pranks? "He took our cameraman's car and filled it with ladybugs," says Parrack. "He goes all out."
Kwanten, 33, also plays small jokes on his pals. "He kept telling me I had a hair hanging out of my nose for three days straight," Parrack says with a laugh. "I shaved my nose and he would still say [he saw] it."
But according to Kristin Bauer – who plays vampire Pam De Beaufort – Kwanten isn't the only cast member with a wicked sense of humor.
"Ryan and Stephen [Moyer] are the biggest pranksters on set," she says. "In the middle of a take, there was sort of an intense scene between Stephen and Ryan, and Stephen pulled out a picture of Ryan that was taken somewhere with a bunch of cute girls. He holds it up on camera and busts Ryan for saying he hadn't been there."
And the good times don't end with Kwanten and Moyer. "Anna [Paquin] is as fun as anybody," Bauer says. "She and I laugh so hard we cry."