Thanks to Gossip Girl, Taylor Momsen is one of the most famous teens in the world -- but she still gets starstruck! The blond beauty nearly lost her cool when Madonna called to ask if she'd be the face of her new juniors clothing line, Material Girl. "It's insane. I didn't know how to handle it. I didn't believe it. I was super excited, it's a big compliment and an honor," Taylor told In Touch at the launch of the brand at Macy's in New York's Herald Square on August 3. Luckily, Taylor immediately felt at ease when the icon showed up to the campaign shoot. "She's super down-to-earth. She's a very cool chick, which is very nice to see. She's Madonna, so you don't really know what to expect when you meet someone so successful," she added. The actress was similarly impressed with Madonna's co-designer and daughter, Lourdes. "She's a very sweet girl, she has great fashion sense!" Taylor gushed. Madonna and 13-year-old Lourdes' '80s-inspired collection is now on the racks exclusively at Macy's.