Yes, that's actually Fergie and yes, she's actually doing a one-arm handstand. While singing into her microphone. Yup.

Fergalicious showed off her aerobic side for an "Idol Gives Back" performance yesterday at the Kodak theater. Her performance included duets with a few other peeps, including Ann Wilson and John Legend.

Just imagine what this fitness diva could do to all those people who call her a butterface. Not to mention that her booty looks like this:

The Idol special will air Wednesday on Fox if you wanna check out Fergie Ferg's full aerobic act...