VIDEO: Bikini Girl Duets With American Idol Judge Kara DioGuardi

The girl still can't sing, but the infamous Bikini Girl showed up at Wednesday's American Idol finale proving she can fill out a bikini top -- thanks to her new assets.

"I'd ask what's new," cracked host Ryan Seacrest, "but I already know!"

Katrina Darrell, aka Bikini Girl, started singing Mariah Carey's "Vision of Love" before being shown up by none other than Idol judge Kara DioGuardi, who sparred with Bikini Girl during auditions. After easily outsinging Darrell, DioGuardi ripped open her black dress to reveal a black bikini. Classy!

Apparently, it was a stunt for charity. See it for yourself: