The actor catches poison oak - which is dermatitis caused by the sap of poison ivy - after going cliff jumping with friends and he has now started to resemble one of the undead.
"I went backpacking over Memorial Day weekend and I just got the worst poison oak," he said. "It was my first time getting it. Dude, it's like everywhere - everywhere! I can't even begin to show you, because you'll get so grossed out. I look like a zombie from Dawn of the Dead."
Zac Efron told his girlfriend Vanessa Hudgens that he has to "air out" awkward parts of his body, but admits any opportunity he gets to wash and soothe the pain feels like "the best orgasm ever".
"Oh my God," Zac said of his treatment, "it's like the best orgasm ever! I'm just airing it out. It just itches too much."