what's katy perry doing on 'greek'?

Hear Casey rocking out to "Waking Up in Vegas" this week in her bedroom.

The ZBZ house is empty. Everyone's gone home. Casey's dancing on her bed and singing her heart out into a hairbrush ... when Rebecca walks in. Oops.

So what about that song? It's by Katy Perry. You probably know what she looks and sounds like, so here's a little background info on this self-described "glamour ninja" who's stormed the pop charts.

Her parents were both pastors, and she sang in church all the time. But not just in church. "My dad would give me $10, which is a lot of money when you're nine, to sing at church, on tables at restaurants, at family functions, just about anywhere," says Katy.

She wasn't allowed to listen to what her mom called "secular music" (non-church music). So how'd she get to be such a pop diva? She was at a slumber party one night and found a Queen record. "The heavens opened and saved me," she says. "From then on, they have been my biggest influence. Their musicality and lyrics were so flamboyant and real. I'd never heard anything like it."

By 15, Katy had chosen to make music her career. She spent time in Nashville developing her songwriting, and at 17 met producer-songwriter Glen Ballard (Alanis Morissette, Christina Aguilera, No Doubt). He spent years working with her, and Capitol Records offered her a deal in 2007.

"Every single one of my songs is drawn 100 percent directly from my life," she says. "I think people can appreciate a songwriter who shows different sides. The whole angst thing is cool, but if that's all you've got, it's just boring. Everything I write, whether it's happy or sad, has a sense of humor to it."

What's your fave Katy Perry song?

Find Katy Perry on iTunes!