Katy Perry -- Birthday (Lyric Video) Download 'PRISM' on iTunes http://smarturl.it/PRISM Download 'PRISM' on Amazon: http://smarturl.it/kp_prism_amzon Lyric video for Katy Perry's "Birthday" from 'PRISM' produced by Mandy Sellick and directed by Aya Tanimura. Follow Katy: http://www.katyperry.com http://youtube.com/katyperry http://twitter.com/katyperry http://facebook.com/katyperry http://instagram.com/katyperry http://plus.google.com/+KatyPerry