I would faint, scream like a little girl and finally i would किस her and hug her. I would thank her for being herself and ask her a million सवालों before she go.
I would stare at her at first and then ask nicely, " Are आप Katy Perry?!?!" Then she would say yes. Than I would be screaming, "AHHHHHHHH! I प्यार you! OMG! I can't believe it is really you!" Then I would hug and किस her and do all kinds of things with her. I प्यार Katy Perry!
i would probably squeal at first, then say hi and tell her how awesome she is and how her संगीत inspires and entertains me, and maybe hug her, if she wouldn't mind :)
I would run up and hug her, tell her how much I प्यार her and ask her if she wanted to be फ्रेंड्स and swap emails so we could keep in touch! If she was upset and cried in front of me, I'd hold her tight and wouldn't let go till she felt better!