The singer got a little too into one of her songs and when she squatted down in her space-age ensemble, she forgot she was wearing a skirt. Or maybe she just forgot that everyone in the audience was taking pictures.
Either way, those in the front couple of rows got even more intimate with the singer than they had expected. Hey, at least she remembered to wear underwear because it could have been a lot worse - or better, depending on where Katy ranks on your personal sexiness scale.
After the concert, Katy tweeted about how excited she was and probably hadn't checked the Internet to see that the sneak peek of her silver underwear was getting more buzz than the concert itself.
Fortunately, it looks like Katy has taken steps to remedy the problem because here is one of her other dresses. Enough said.