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JOEL & BENJI OPEN SHOP

Benji, Joel and older brother Josh Madden, 30, celebrated their new store DCMA Collective, which sells head-to-toe rocker gear, in L.A. March 14. "It's like another baby!" joked new dad Joel. Girlfriend Nicole Richie kept checking on their 10-week-old daughter Harlow even though "I've only been gone an hour." Harlow is a fan: "[DCMA partner Tal Cooperman] and I have been making special stuff for her because I don't like to put her in black," said Richie, who also plans to design her own jewelry line. Paris Hilton wore a custom DCMA (a nod to the Maddens' home turf of Maryland and Washington, D.C.) T-shirt with crystals. "She did that herself!" gushed her boyfriend Benji. Pete Wentz, Christina Milian and Ja Rule were also at the bash sponsored by 944 magazine and RCause.org. Nicole and Joel left early—even so, said Joel, "it's nice to get out of the house!"

FOR SALE: Women's "Stacked" T-shirt, $25 (323-677-2125); "Knuckles" belt buckle, $30 (dcmacollective.com)

NICOLE'S BIRTHDAY SURPRISE

Nicole Richie threw a Boyz N the Hood 29th b-day bash March 11 for Joel and 50 pals (including Benji and Paris, natch) with a cake featuring late rapper Tupac Shakur. "She knows I love my West Coast gangsta rap," said Joel. "Leave it to Nicole to make fun of you at your own party!"