Credit: INF

The cast of HBO's True Blood not only strip down for the new Rolling Stone -- they also bare all about shooting the show's racy sex scenes.

Says Alexander Skarsgard (who plays sexy vamp Eric): "I don't want a sock around it, that feels ridiculous. If we’re naked in the scene, then I’m naked. I’ve always been that way."

Anna Paquin says she covers up -- somewhat. She reveals that she wears a "patch" – a thong-like attire with the sides cut off – while filming nude scenes as her character Sookie Stackhouse.

As for her costar (and real-life fiance) Stephen Moyer (who plays Sookie’s vamp love Bill Compton)? He wears a sock on set -- out of consideration for others. See behind-the-scenes pics from their RS cover shoot.

"I've got nothing to hide," he says. "I just think it might be embarrassing for the crew."

True Blood creator Alan Ball says all the racy sex scenes and nudity are necessary. More photos of stars posing nude on RS.

"To me, vampires are sex," he says. "I don't get a vampire story about abstinence. I'm 53. I don't care about high school students. I find them irritating and uninformed."