This seems to be the default pose to use when picturing Those Crazy Teens in the '50s...
I guess her pose is supposed to symbolize the playfulness and nonconformity of youth, and perhaps the rejection of the staid societal norms of the previous generations. Then again, maybe she's just wearing antigravity socks.
Actually, in the 1956 ad above, her inverted body actually serves the product in that it shows how comfortable it is to lie directly on a carpeted floor. The same pose is also found in this 1951 ad, coupled with some hip teen lingo to show how "with it" Post Toasties are, Daddio:
The pose probably reached its apotheosis in 1963, when uber-teen Ann Margaret lolled on her back for all of America to publicize the movie version of "Bye Bye Birdie."
Labels: Celebrities, Entertainment, Movies, Pop Culture, The '60s, The 50s