Katy Perry's been hanging out with her BFF Rihanna... any last minute tips for our gal, RiRi? This image appears in the gallery:Jingle Bell Ball 2013: Road To The Ball 23. Katy Perry's been hanging out with her BFF Rihanna... any last minute tips for our gal, RiRi? Picture: Instagram 30 images See the full gallery: Jingle Bell Ball 2013: Road To The Ball