Britney Spears -- Inside Out Girl

12/3/2009 2:03 AM PST
Considering all the people paid to watch her back, you'd think one of 'em would have told Britney Spears her sweater was on inside out.

28-year-old Brit Brit got her b-day shop on with BF Jason Trawick yesterday at Fred Segal -- where the paps actually sang "Happy Birthday" to her ... without the assistance of a backing track.