BSPEARSTINKERBELL122007_23.jpgBritney Spears BSPEARSTINKERBELL122007_16.jpg With little sis Jamie Lynn still laying low, Britney continued to bear the brunt of the questioning about the newest addition to her family.

Last night, while looking for gifts for her family at a Hollywood souvenir shop, Britney clammed up as soon as the subject of her impending nephew (not to mention aunthood) came up.

In fact, by the time she did open up to the paps, Britney was outright denying Jamie Lynn's pregnancy - again!

Asked if she could confirm her sister's pregnancy for X17, Britney turned to the camera and clearly said "She's not pregnant".

We don't know what's behind Britney's repeated denials - but now we gotta find out!