Your Song Rita Ora
Starbucks have responded to Katy Perry's Twitter with a Britney Spears diss.
Katy Tweeted: 'Today I quit my beloved coffee & make the switch to vitamin B complex. Don't worry @starbucks it's not forever'
In response Starbucks Tweeted: ' It's ok. Today I made the switch from California Gurls to Hold It Against Me. Don't worry, it's isn't forever'