Get "Birthday" from Katy Perry's 'PRISM': http://katy.to/PRISM
Katy Perry Complete Collection on Spotify: http://katy.to/SpotifyCompleteYD
Katy Perry Essentials on Apple Music: http://katy.to/AMEssentialsYD
Watch your favorite Katy videos on YouTube: http://katy.to/MusicVideosYD