Rihanna has told Katy Perry she wants her to ''spank'' her bottom.

The 'Firework' hitmaker took to Twitter to quiz her friend on why she wasn't invited to the King of Diamonds Gentleman's Club on Saturday night (20.04.13) after she saw the saucy snaps of Rihanna cavorting with the strippers.

Katy tweeted Rihanna to say: ''Ermm... I was in LA Saturday night... Should I be proud or offended I wasn't invited @rihanna #WHOISTHISDOPPLEGANGER (sic)''

Rihanna replied almost immediately to let her best pal know she had been partying in Miami.

To make up for the missed lapdancing fun, she told Katy she could slap her butt the next time they hook up.

Rihanna, 24, tweeted: ''Errm I wasn't! Lol! #miaminights Howeverrrrr ... I'll still let you spank me! (sic)''

Rihanna dropped into the strip club to see how the girls danced to her music and ended up staying at the bar for several hours and spending $8,000.

Writing about her wild night on Twitter, the 'S&M' singer posted: ''Last night one of my fantasies came to life! I got to see K.O.D strippers dance for me to the stripper song I made! (sic)''