From PEOPLE Magazine Click to enlarge
TOMMY LEE

"My man cave is my home recording studio. I call it 'the Atrium,' " says Lee, 48. Three main rules that apply once you're inside?

1. The lights have got to be dim. "When they're too bright, it's a bummer," says Lee. "This is not an office; this is a recording studio!"

2. Playback must be loud at all times. "None of this 'Oh, just listen closely,' " he says. "We don't do that around here."

3. No drinks on the console and no cigarette butts on the floor. "That's about it with the rules," says Lee. "Pretty much anything else goes!"

LL COOL J

"I wanted it to have a cozy feeling," says LL Cool J, 42, of his customized trailer on the set of NCIS: Los Angeles. "Every morning when I come in, I light some incense, have some tea and do some sort of exercise." But once he leaves for the set, that's when all hell breaks loose. "I'm in here getting ready to jump over cars, shoot bazookas and blow stuff up!"

JOHN STAMOS

"I have a lot of parties here," says Stamos, 47, of the man cave in his Beverly Hills home. "It's my music room, my jam room." The space has been graced by an impressive array of stars. "The last time Adrien Grenier came over, he played drums for most of the night," says Stamos, who also recently hosted Rob Pattinson. What about the ladies? "Cloris Leachman showed up at my birthday party, grabbed the mic and sang 'Happy Birthday.' "

ZACHARY LEVI

"I don't think it's a man cave as much as a child's dream cave," says the Chuck star, 30, of his home's garage, which contains a motorcycle, a collection of video games and a Ping-Pong table. "Every boy grows up dreaming of those things-and of a girl who digs that stuff and will spend time with us in that space."

NATHAN FILLION

The star of ABC's Castle just bought a new home and made building his man cave a priority. "I converted one of the bedrooms into a home theater," says Fillion, 39. "I got a big 3-D TV; there's surround sound and an Xbox." But Fillion also made sure the space caters to his softer side. "There are big pillows and blankets. When I'm watching TV, I like to put on sweatpants and a T-shirt and put a blanket around me, especially if it's a scary movie."

JASON SEGEL

The How I Met Your Mother star-who also cowrote and stars in next year's new Muppet movie-is most at ease in his living room, surrounded by his favorite puppets. "Whether or not a girl thinks the puppets are sexy depends on how smart she is," says Segel, 30. "If she realizes I'm doing The Muppets, she'll think it's cool. Otherwise I'm just a weirdo who plays with puppets."