The 'Game Over' singer told Metro that her tour manager tried to spare her blushes during the incident.
Brown said: "It was a great gig, other than me almost corrupting the children. It was at Bestival. I was parading my bum in front of the kids.
"My tour manager ran on stage with a sarong. I wasn't wearing any knickers and the hole was getting bigger and stretched up to the embarrassing bit."
She added: "I told him to f**k off. When I realised he was helping me I apologised."
Earlier this year, Brown revealed that she had turned down the chance to appear in US Playboy but would be happy to be shot in a "really classy arty way" for the French version of the publication.