Pop beauty Katy Perry took to her official Twitter page earlier this morning to ask BFF Rihanna why she wasn't invited to a naughty night out after seeing photos of the 'Umbrella' singer's party weekend online.

Perry wrote: "Ermm... I was in LA Saturday night... Should I be proud or offended I wasn't invited @rihanna #WHOISTHISDOPPLEGANGER."

Rihanna quickly responded to her and replied: "@katyperry errm I wasn't! Lol! #miaminights howeverrrrr....I'll still let you spank me!"

'Teenage Dream' superstar Perry, who has been close friends with Rihanna for a number of years, then returned to the social networking site and added:

"Don't worry @rihanna I'll make it up to you at Barclays... 💵💋💵💋 Or more like let you make it up to me... Hehehe @rihanna 💋💵💋💵."

Meanwhile, Katy Perry has been working on a brand new studio album and recently joked that the writing process has been "an emotional abuse session": "It's like the dream team. They push me the most, and also argue the most. It's an emotional abuse session. I'm a student of life. Words are like little treasures. I put all of my ideas in a folder, whether I read them in newspaper or through a conversation with friends. I've got years of titles and things I want to write about."

Watch adorable footage of the girls' friendship here: