Just when you thought you knew everything there was to know about former MTV queen Jenny McCarthy, the tell-all celebrity now admits to having sex in the Grand Canyon and giving a lap dance to octogenarian actor Kirk Douglas.

McCarthy, who stars opposite Douglas in the movie Diamonds, tells Maxim that she gave the veteran actor and recent stroke victim a surprise lap dance during his 80th birthday party on the set of the flick. "We even got pictures of me shaking my booty in his face," she confesses. "I figured, what the hell, when you turn 80, wouldn't you like some little hottie to give you a lap dance?"

McCarthy admits she's a sucker for little old men ? they're "so wise and cute," she explains ? but the real love of her life these days is Diamonds director and new hubby John Asher. And she says the best thing about being in a relationship is the ability to have sex "anytime you're horny.

"Like, there was a time when I had sex at the bottom of the Grand Canyon," she says. "We hiked for five hours in 100-degree heat and then just went at it once we got to the bottom. It was amazing."

The 27-year-old McCarthy attributes her active libido to her Scorpio birth sign: "That means I'm a businesswoman in public and a total slut in the bedroom. I actually think about sex a lot more than I do it, but I'm into eroticism. Let's just put it this way: I like it all." ? Rich Brown