It seems the Ultimate Big Brother house may be proving a confusing place for some of the contestants.
Nikki Grahame may be 28, but perhaps a little refresher course in the birds and the bees wouldn't go amiss.
Nikki's confusion arose during a conversation with Brian Dowling about fellow contestant Nadia Almada's slightly moody behaviour.
Nadia was born a boy, but had a much talked about sex-change operation before winning the fifth series of Big Brother in 2004.
Despite overwhelming anatomical evidence to the contrary, Nikki's explanation for Nadia's moodiness was simple: "Maybe Nadia is on her period?"
Ever the diplomat, former airline steward Brian left a pregnant pause before replying: "Yeah... unlikely, but maybe."