Plastic fantastic! Katy Perry flashes her knickers in completely see-through skirt

But she really outdid herself when she donned a completely see-through skirt that flashed her knickers for her latest gig.
The hottie, who turned 29 last week, wore a silver bodysuit under her plastic skater dress to cover her modesty, while cinching in her waist with a metallic silver belt.
The singer looked like she was
returning to her space-age 'E.T' days as she slicked on some bright purple lipstick.

Katy was launching the album for iHeartRadio in Los Angeles, and took to the stage to perform several songs from the new record.

The busty babe was glowing as she gushed about how boyfriend John Mayer influenced some of the songs on Prism.

But nothing could really distract from the fact that you could see every inch of thigh through the thin plastic skirt.
Katy added even more sex appeal with raunchy fishnets and a pair of skyscraper block heels.
The 'Roar' singer kept her hair in 50s pin-up curls as she chatted to former Saved by the Bell star and presenter Mario Lopez about her new album Prism.

And it seems like Katy can't really shut up about her musician fella, after she discussed her relationship with W Magazine.
Katy, who was previously married to lothario Russell Brand, said: "I actually am dating my crush. I had a crush on him for a long time."
This is the singer's second go of it with Mayer, who previously dated stars like Jennifer Love Hewitt, Taylor Swift and Jessica Simpson. He offended the entire female population several years ago after he told the press that Jess was "sexual napalm" in bed.
Charming.
But at least Katy seems happy for now. The couple were seen partying in east London after Katy's performance on The X Factor on Sunday night. The curvy beauty wowed in a tiger-themed dress that flaunted her eye-popping cleavage.