Did Katy Perry just do a "geisha" performance at the American Music Awards? Yes. Complete with “geisha” costume (with slits up to the butt), stunted pseudo-Asian dance/walking, cartoon Kabuki makeup on her backup dancers, lots of fans, people in “Oriental” costumes beating drums, rice paper screens, and blown-up versions of the cheap paper umbrellas you put in your drinks.

Is it racist as fuck? Yes.
Is it the worst thing ever? Also yes. 
Did the song have ANYTHING to do with Asian culture? No. 

Is she the first pop princess to pull this shit? Absolutely not (for further reference, see Rihanna/Coldplay’s “Princess of China” and Gwen Stefani’s L.A.M.B. phase)