Believed to be a shortened version of "He's flapping like a big girl's blouse" (from the appearance of a blouse drying in the wind) used to describe an indecisive person.
The first recorded usage is spoken by the character of Nellie Pledge (played by comedienne Hylda Baker) in an October 1969 episode of the television sitcom Nearest and Dearest. It has been suggested that Baker had previously used this expression in her stage act.
big girl's blouse (plural big girl's blouses or big girls' blouses)
- (idiomatic) An effeminate or weak man, a sissy.
- 2002, You can see why people might think you’re a bit of a big girl’s blouse, because you have manicures, sunbeds and bleach your hair. — Marie Claire, June 2002 question to David Beckham