The Firework singer, who is currently on her California Dreams world tour, says she prepares for gigs by saying a prayer with her crew.
She told Entertainment Weekly magazine: 'I have this little box of prayers, but they're very small, simple one-line prayers, and I pull them out and read them out loud.
'Everybody either agrees or disagrees with them, and then we just put our hands in a pile and dedicate the show to something funny or stupid.'
The 26-year-old star, who is married to British comedian Russell Brand, added: 'When we were in Nottingham, we dedicated the show to Robin Hood.'